@RKTGX95:
i don't want him to catch up as quickly as possible, but so that he enjoys the journey. (which is what One Piece is all about) And for that the Anime is at least equal to the manga. Also, i lot of the One Piece fillers, in my opinion, are great. If you exclude the Warship arc the fillers are great fun to watch (especially the obvious G-8). I wouldn't say that Skypea and Alabasta aren't interesting, even if they are longer in the anime. Sure it is annoying on a weekly basis but as a whole and watching continuously it works quite well. My worries are from bad fillers (like warship arc and pre movie 10 and 12 level of fillers. most of the others looks fine to me)
Oh ok. I was just concerned also because of the sheer quantity of eps he may lose interest. So basically you're asking is what fillers he should and shouldn't watch? I actually don't mind fillers that much either but some people are turned off from them because they don't advance the story much. I haven't seen all of them but G-8 and extended Davy Back were fun watches… I also liked the one after Davy Back with the kid and his sea horse. I forgot what it was called but it was interesting. As for ones to skip, definitely skip those Alabasta sand pirate ones. Those IMO were not entertaining and just dragged on. I also thought the filler right after Enies Lobby wasn't that great, mainly because I thought Don Accino was stupid lol. Anyway that's just my thought.
The movies are pretty cool too, I'd reccomend he watch some of them. I had a friend of mine who was getting into One Piece watch the Alabasta movie instead of each ep, sure a lot was cut out, but he got the gist of it. But even the Toei productions can be entertaining, I particularly liked the 6th one.
Hope I helped!