FMA is the best out of those 4, with Trigun on a close second.
Naruto might have been the 3rd, if it just hadn't started sucking, like it does now. It was really cool in the beginning.
Inuyasha I haven't seen too much of, but from the 20 or so episodes I saw, it didn't look too interesting.
However, the best series I have ever seen is Scrapped Princess.