Remix 1 is better than Remix 2.
Remix 1 is the best format to play several of its featured games. A lot of those games aren't worth more than an hour of dicking around on their own IMO, but having a challenge and achievement structure built around them adds a lot of appeal and replay value for the more arcadey, score- and time-based games that make up most of its content. Going for 100% forces you to learn some nuance and tricks in these games that you might have forgotten or never knew about in the first place, and after doing so, I think you'll feel like you've gotten the full experience out of several of those games even without having access to the full games themselves. You just have to be able to put yourself in a 1985 mindset and accept that most of these games are built around much more limited and rigid controls, among other things.
Remix 2 often felt like little more than a tutorial for its games. I'd rather just play the individual games.