I like the anime equally with the manga now, as I am an addicted OP fan nowdays. before I became this addicted, I enjoy the anime more than the manga, maybe because I enjoy watching more than reading at the first place.
other than that, I love the anime because the moving picture, colour pics, voice actors, BGM, and the better emotion I can get while I watch the anime, (I don't have that great imagination in my mind ^^; ) for example: I cried in every flashback and conclusion in anime (yes, I'm that kind of sappy person ^^) but while reading the manga I only feel touched. (I did cry at chopper's flashback, and Sanji's goodbye scene)
I even enjoy the filler eps gasp In fact, I never knew it was filler eps until I joined this forum. I enjoy it because it has a different story arc from the manga, and as long as it's One Piece, I'll enjoy it :P well… I must admit that sometime I frowned (when watching fillers) and think that something is wrong ie: 'Nami isn't that mean, is she?' or 'whew... why Sanji became this obsessed over Nami (too obsessed)' etc. but still I enjoy it, as well as movies and specials.
and I do think that several things are clearer in the anime, well maybe it also to drag some time, but it does explain something, ie: what happened before Zoro fight with the sharks at Skypea altar, the fight between Monbran Cricket &monkeys brothers and Bellamy. things like these I can't figured out when I read the manga.
but at the end, these are just my opinion :)