I agree with Veks on RandomAnime. I have no idea why it would ever be popular.
BESM is a fine game, but with each new edition, it edged closer and closer to being GURPS with 2 dice rather than 3 (3 traits rather than 4, etc). If it's a mainstay RPG for you already, that's fine, but if you have access to any other "generic" RPG, I don't see any point to picking up BESM. It takes just as much work to put together a good BESM campaign or character as it does to put together a good GURPS campaign or character.
I have OVA, I have run OVA, I love OVA. It's simple, sleek, and right to the point, and the dice mechanics make for some great fun, lots of roll-and-shout moments, and the core combat system is inherently interesting enough to kee my combat-monkey players rapt at attention, while simple enough to keep my flakey drama players happy. It's actually one of my favorite systems, though I haven't had much use for it recently, precisely because it manages what few "lite" systems do: It doesn't dumb down the rules to the point where you wonder why you need them at all.
I highly recommend the game.