SG-1 is more militaristic in its setting. Everything is an op and mission with the fate of the world on the line. I personally like the thrust of discovery that its earlier seasons had along with world building which they returned to in the last 2 seasons.
SGA is somewhat inverted in the sense that it's less militaristic and more civilian so there is more focus on what do we need what is the world like. The problem with it is that it gets somewhat drab in season 3, 4, and early 5, but near the end it starts picking back up again. Unfortunately we're left with many questions about the world that as far as I know are never resolved. It mixes those elements I like from the early and later seasons of SG-1, but it never comes to fruition due to canceling...
Characterwise... Shepherd is a younger clone of O'Neill. Teyla is the strong female character, but lacks the intelligence of Carter... She more or less plays an Amazon. Ronon is a more talkative, less open Teal'c that came into the series later. He grows a little bit, but is largely stuck in the noble warrior gimmick. The original 4th is your common rookie and doesn't really grow. he just changes. McKay is a whinier wimp that the Soldier originally think Jackson is. He has low morals, and he's dumber than Carter. They pretty much attempted to shove all the "smart people" stuff into him. Teyla plays the culture role of Daniel, but she has little knowledge so doesn't really work. And the "O'Neill is smarter than he seems" is tried to be replicated here, but ultimately it comes off as the message "Jocks are smarter than geeks, they just don't show off" due to McKay's character... Shepherd and McKay are the most fleshed out and their relationship resembles a toned down version of O'Neill's outbursts against Daniel or Carter when they are being smart/difficult.
SGU... is a slog to get through... mostly because the main focus is on Eli, the supposed to be main character, being treated like trash and getting little development. OR because the focus is on the head military and head science guy clashing, mostly because the head military guy knows nothing and the head science guy keeps everything a secret, sometimes for very good reasons, other times not so much. It's largely teen drama, even when focusing on the older characters, and the first season takes the "OMG everything is breaking" of SGA's first 2 episodes into overdrive with it lasting practically the entire first season. By the time they get to something really interesting the show was canceled and we don't know anything about their fate, nor do we get any answers to the questions that SGA or SGU raised, which are really interesting with respect to Ascended beings. And worse is that they likely will never be resolved due to IP rights being bought up by Emmerich who has no intentions of sinking money into the TV franchise, but continuing the movie franchise.
The main differences are pretty much the thing that you said you liked.
SGA characters are mixed around clones of the characters you see in SG-1.
SGU is all teen drama characters.
SGA you'll probably like, but SGU... I'd push through because it does reveal some interesting questions with regard to the universe, but it is also highly frustrating, bland, and missed the mark on so many things, but there are some good things about it too.