Contrary to popular (well, Vader's) belief, a Sith warrior is not immortal. Even though Vader is powerful and well armored, a frontal assault on a Rebel base would be little more than suicide.
Here we can see a half-dozen troopers making short work of a Jedi Knight
There's also the fact that Vader needs to report back to the Emperor on what happened as well as planning his next move against the person in the X-Wing
Darth Vader regained control of his damaged TIE fighter. As he headed
for the nearest Imperial outpost, he was not preoccupied about how he
would explain the loss of the Death Star to the Emperor. Tarkin had
been responsible for the space station and its vulnerabilities, and
the Rebels had been more cunning than anyone had anticipated. There
was really nothing more to say.
But there were plenty of other things to think about. Before Vader had
been knocked out of the trench, he’d recognized the Corellian
freighter as the same ship that had delivered Ben Kenobi to the Death
Star, reportedly from Tatooine. Vader wondered why Kenobi had been on
Tatooine, and how long he’d been there. Then Vader thought of the last
X-wing pilot in the trench. He was so strong with the Force.
Vader wouldn’t rest until he learned the truth. - Star Wars: A New Hope - Junior Novelization