I haven't played 6, but from what I've seen 5. 6 may have been better if they didn't focus as much on action as 4 and 5 do and had a plot that wasn't so...well...whatever 6's plot was going for. Still, Chris' ending is probably the most touching and sad ending of an RE game.
Before you die you see the Tails Doll---Backdrop Observer of the Metroid: Other M board Apparently Edward: Wise Old Sage of Korodai
5 is most definitely the better game. Wish that team worked on 6. What we got was a mess of a game that tried to be horror and action, but provided mediocre portions of both and a ton of QTEs (which somehow managed to be more obnoxious than they ever were in 4 and 5).
At least 5 had an actually good campaign. Only thing that really shines in 6 is Mercenaries mode, and I did not pay the $60 just for that bonus mode.
They both were chores to play but 5 is preferable.
5 is a chore like milking a cow; it takes a while but there is some reward and you don't mind doing it everyday. 6 is a chore like shoveling out the barn; it takes a long time you get covered with crap and after you're done you're ready to let someone else take over.