For me it would be:
1. One Piece (By far the best of these in my opinion. Most compelling plot, definitely the best character development of these, and remains awesome in spite of being longer than all of the others. Character backstories are amazing and the fights are great. May not always be as flashy as some Naruto or Bleach fights, but One Piece doesn't suffer from a lot of plot-induced idiocy when it comes to fights like those two. Fishman Island arc was kinda meh, but it's no worse than the bottom of the others)
2. Fairy Tail (Very enjoyable, though far from perfect. At its best it's a high spirited action Shounen with a lot of good fun and a likeable cast. Quite similar to One Piece, though not as awesome. That said, Fairy Tail does have a few bad plot-induced fight victories and in particular, the arc before the time skip and the time skip itself bugged me a lot. Overall though it's not too bad and it's definitely worth it)
3. Naruto (A mixed bag. At best you have stuff like Kisame's awesomeness and the Minato/Kushina character development, at worst you have Sasuke melodrama and wasted potential like Uchihas vs Kabuto. Though overall I would say I enjoy Naruto, it can be pretty bad at its worst and it's nowhere near as awesome as it was much earlier in the series)
4. Bleach (Also a mixed bag. Beginning is great and the last arc has also been enjoyable, but everything else is pretty bad. Much of Bleach has been filled with mindless action with almost no plot and really poor character development. Not to mention a lot of very, very repetitive usage of the same story elements as well as Fullbring arc just being entirely pointless. That said, Bleach has been picking up recently and it really does seem like this was the arc that Bleach should've gotten to long ago. If all goes well, Bleach will continue to be interesting, I just hope that it won't drop back to mid-Bleach quality once again)