Dare I say, gimmicks.
I often like special control-methods and things that might take you out of the world a bit but can be fun in its own right. They are often a hit or miss type of thing, but when done right they are often a reason why I love some games.

Motion controls are awesome and when done right can substantially elevate a game.

Dialling in a shot with gyro in Sniper Elite 4, flicking the remote to propel Mario into the air or smash a baddie in Mario Galaxy, or slashing foes in the swing of my arm in Red Steel 2 were all phenomenal experiences that a standard pad just can't replicate.

I genuinely love the 3D graphics of the 5th generation (and the 6th gen for that matter) , when I see something like the graphics of the old Tomb Raider games, Resident Evil, Panzer Dragoon, Medal of Honor etc. it's like abstract art to me, there is some mystique to the esthetics that is just lost when they try to make the games look more "beautiful". 

I also like the controls of a lot of the games from that period, despite people calling them "dated", I like that there wasn't a "standard" on how games should control, but developers actually experimented with different ways.

Also linearity and shorter games are generally (not always) a plus for me.