Well, when you think about it, it was his love for Padme that helped save him in the end. Just as it had sent him over the edge - along with other underlying psychological issues that were plaguing him - and propelled him toward the Dark Side in the first place.
While Leia very much resembles Padme, in both looks and intelligence (not to mention political prowess), it's Luke that's most like her. Leia may have a lot of the same upbringing, education, and career opportunities that Padme had, but the core of her nature is very much like Anakin's. Brave, passionate, fiercely stubborn, an excellent fighter, a brilliant strategist, and yet someone who is also easily capable of giving into the Dark Side (given the amount of pain she's both experienced first-hand and witnessed others suffering through due to the Empire and it's policies). She's definitely more level-headed than Anakin was at her young age, but again, this is a reflection of her intelligence and pragmatism
Luke, who is the spitting image of his father and has many of the same hobbies and interests as Anakin did (especially since they both grew up on Tattooine), is of the exact same-nature as his mother. Kind, compassionate, tender, and loving, he displays many of the same qualities at the core of his nature that Padme displayed herself. He's smart and a more-than-capable fighter, Jedi, engineer/mechanic, and pilot, no doubt about that...but those are reflections also due to his career choice/destiny, hobbies, and education. His true nature is much more sensitive, much like Padme's was when you got to know the very depths of her true heart...
This, I believe, is why Luke was able to save his father. Much like Padme, Luke displayed a lot of compassion and belief in Vader, when Vader had none for himself. Padme, upon knowing that she was about to die, declared that there was still good in Vader/Anakin, much like Luke did when he confronted Vader for the final time in Return of the Jedi. I surmise that, being reminded so much of his wife by their son was what spurred him into turning on Palpatine while witnessing Luke's torture. I'm sure this brought up a lot of memories and an awakening of the truth in Vader/Anakin, which finally prompted him to betray the Emperor and protect Luke, finally ending the dominant hold of the Dark Side on the galaxy. I say this brought upon an epiphany because I believe, while witnessing Luke being tortured at the hands of Palpatine and seeing/feeling how much Luke was like Padme in his true nature, this forced him to realize how much of a second-chance this was to save Padme (Luke), like he truly could've long ago had he not believed in the lies of Palpatine. And obviously, after realizing that Palpatine HAD lied to him in order to trick him to turning to the Dark Side (again, there are other psychological factors here when it comes to Anakin and his quest toward darkness), he wasn't really anxious to repeat that same mistake again. Nor bear the unending regret and self-loathing that would've truly destroyed what was left of his soul had he not stepped in to save Luke.
So, his love for Padme - which was rekindled due to the love for his son - is his saving grace in the end. Simply put, there were a lot of errors that were put into play: a lot of the responsibility for those errors falls on Anakin/Vader and Palpatine, but also the Jedi too for their hubris, arrogance, and rigidity with traditions. His love for Padme was something pure that, unfortunately due to Anakin's insecurities, fears, and Palpatine's manipulations, was twisted into something dark and possessive/obsessive (which some may argue was already there while he was a Jedi anyway). Luke, who came blazing into his life like a beam of pure light out of nowhere (twenty-years of believing he was dead, along with his mother, left Vader in total darkness), was a reminder of the purity of the love Anakin held for Padme and reawakened his soul and emotions once more.
After all, the reason why Vader was so powerful with the Dark Side was not just because he was the 'Chosen One,' but because of his self-loathing, depression, crippling guilt, and regret. I agree for the most part with a lot of the answers given on here, especially by ASH-Aisyah and StarWarsQuestionsanswered. In fact, if you get the chance to glimpse the comics that tell Vader's story a year after his full-transformation and transition to the Dark Side, he actually becomes suicidal at one point due to a vision of Padme's ghost and the guilt and remorse he feels in her presence (about what he did to her, what he's become, and what he's done to thousands of others for the sake of the Empire he helped to create). He's also someone who's left isolated most of the time, as he bears no other relationships with anyone, except with his Master/Emperor Palpatine (if you can call it that) and a few of the prominent officers and generals within the Imperial army. But for the most part, they all believe him to be an unfeeling cyborg/machine that carries out the whims and wishes of the Emperor personally. There's also the fact that he's imprisoned within the biomechanical suit that keeps him alive and can only have his helmet removed once he's within his oxygen-rich, meditation sphere. Which means there's only total silence and his thoughts and emotions to keep him company while he's in there. You can imagine how horrifyingly traumatic that must be for someone who's a lost soul suffering from depression, soul-crushing guilt and regret, and also grieving for the lives he took, especially his wife and children (until he learns the truth about that situation, anyway). There's also a numbness that prevails within him at all times, which I believe is what allows him to push away those deeper feelings and give into the anger and childish belief that everything that happened to him is due to outside influences or betrayals (Obi-Wan, the Jedi, Tusken Raiders, Palpatine, etc...). But that self-hatred, along with the hatred he has for all of life, the Jedi, and the galaxy (because Padme isn't there with him and was taken from him), combined with the anger, guilt, regret, despair, depression, and childish reluctance to take the blame for the crimes he committed (against himself, Padme, the Jedi, and the galaxy itself) are what serves to make him a very powerful Sith Lord. And again, Padme is there too, even in his darkest moments and feelings.
So, to me, if Padme is truly that much a part of him, and that he is the child created by the will of the Force itself (though some debate that topic as well), then Padme is very much a big reason for the purpose of his existence in the first place...aside from the whole prophecy/being a Jedi/destined to bring Balance to the Force thing, etc... (lol). They were simply meant to be and there was nothing that was going to undo, or change, that very simple truth. Anakin had to fall to the Dark Side to understand its treachery, malevolence, and unquenchable possession just as he had to start out as a Jedi to understand the Light Side and it's compassion, peacefulness, and unconditional love. Can't tip the scales if you don't comprehend what both sides weigh in on and THEN decide what side deserves your support. He's a Shakespearean tragedy, in a nutshell. shrugs
Did Anakin/Vader love Padme when he choked her? Yes, absolutely. But again, it was twisted due to Palpatine's manipulations, the pressure of living a secret-life, the desperation to save Padme, the need to be powerful enough to sustain her life and the baby's, feeling guilty for the lives he had taken, the destruction of the Jedi and the temple that was wrought by his hands, believing Obi-Wan had betrayed him by telling Padme his recent activities, and believing Padme had betrayed him by bringing Obi-Wan to Mustafar to kill him. He lashed out in anger and hatred, and much like when a regular person does so, it wasn't until after he had committed that assault against Padme that he realized how utterly far he had fallen and how terrible he must truly be (not that any of that excuses what he did or makes it okay). To be told later that he was the reason she died...that he alone was responsible for the death of the very person (people) he wholly loved and wanted to save above all else...well, you can imagine how terrible it must've felt for him. Especially when waking up in that new suit (and lifestyle) and wondering why she wasn't there...if she'd even look at him the same way or love him for the monster he became mentally, emotionally, and now physically. Or if she'd lost the baby because of him or had the baby and was recovering (and if she did/was, would she even allow him near the child after finding out he'd killed younglings...).The fact that he asked for her at all after going through such a painful surgery (that took place for days, mind you) shows just how much he truly did love her...it just got buried under his misplaced rage and hatred.
Immature, guilt-laden, desperate, power-hungry, full of self-hatred, angry, confused, and feeling immense regret; yes. Not in love with Padme, even during that passionate outburst of hatred and anger? No.