There are two anime series which I have just finished watching, One piece (Yes, all 457) and FMA brotherhood. At first I stuck to the subs made by Kaizoku-fansubs for OP but later switched to other fansubbers because they take way too long to sub a single episode. It starts out very childish but later gives a more darker feel in the Impel Down saga. The Whitebeard Saga currently in the making is probably going to be the best saga because a certain someone dies. I would only recommend watching the series if you can put up with filler episodes (A lot of them).