From my last purchase, the important part I remembered, basically just stay away from anything "flagship." The mainline stuff, the things everybody knows because they're the only ones to get all the ad space and shit. For galaxy, that'd be the S series. The number of people that will actually ever utilize the top-of-the-line models to their fullest potential is probably triple digits or less.
I personally like hitting up mid-range models, the A series. Some hardware compromises you'll probably never even notice, saves big money.
Then I think there's some region specific lines you wouldn't need to worry about.