They're both fucking great bands. Nirvana 2002 and Nirvana. Really lame to argue which one is better as they're from completely different genres of music. But the undeniable fact is that Nirvana was formed in 1987 and Nirvana 2002 in 1988 so the grunge one didn't steal the name.
Kurt Cobains Nirvana was formed in 1987, one year before this one. They also released their first full-lenght called 'Bleach' in 1989 while Nirvana 2002 only had two demo's in 1989. Comparing the two or bitching about who has the right to use the name is unnecessary and stupid.