I do actually both PVP and PVE and would find it rather boring to do only one of both.
I'd categorize raids into three different types:
That's content my raid group is actually trying to clear.
For new raid content fun is finding out about the boss mechanics and evolve the tactics ourself.
For hardmode/nightmare it is fleshing out the tactics and to improve as a team until we master a boss.
- Raids to gear up:
Raids we do regularly to get better gear. It's routine spiced up with jokes and smalltalk in TS.
- Fun Raids:
Raids done to chill, maybe equip a twink or two and laugh a lot. We create our own level of difficulty by trying to creativly kill certain raid members or maybe wipe in an as absurd way as possible, completly ignoring mechanics, pulling as muss adds as we think we might handle or even more, doing 8/16 man raids with as small groups as possible. Such things. We are not the most disciplined lot .
Sometimes I do some PUG raids to get acquainted to other people and guilds and to pick up some promissing players for our guild (of course only those without a guild
All in all for me it's the people of my guild and friends that make raids fun.