Both! Why not have a launched ride where, instead of hitting brakes at the end, you hit the bottom of a chain lift [:D]
In all seriousness though, I much prefer launched rides, partly because I have vertigo and really tall chainlifts have been known to make it play up a little, and I just love the feeling of acceleration that you get from launched rides. One of the first things I said after getting off Rita yesterday was "if it were up to me, all rides would be Intamin Rockets"
, while I obviously don't actually believe that, it's just... yeah. I WANT to ride Dodonpa!!!
Obviously it would get boring if all rides were launched rides, but that's just what I prefer [:)]