BESM d20
BESM d20 does indeed look nice, but on the whole, I found it quite disappointing. The book does not do what it claims, which is be compatible with any d20 seting or book. They alter the base mechanics of the game in several places. Most notably they change combat completely, in a way that, I feel, is detremental to the anime genre (its far too easy to hit a target... if you don't buy armor you die). The special abilities are nice as are the weaknesses. Its not 3.5 compatible, but they are supposed to be updating the classes to the 3.5 versions.
If you want to run a campaign from the beginning, with different rules from the normal d20, it might work for you. If you want to use it as a tool kit, it won't work at all.