I've had ether (pharmecutical grade) which was quite interesting and quite euphoric... It was also pretty addictive while high, I found it easy to get lost in a different thinking state. Much better then alcohol in my opinion.
Amyl nitrite is fairly interesting but it seems more like just an intoxicant rather then euphoria, it has altered my high quite a bit on pills and sort of sedates you (relaxes your muscles) and makes it more smacky in my opinion, but I don't think fun describes it. It just well... intoxicates you.
I would say the best in order of preference would be nangs, then ether, then amyl. Never had much curiosity towards other inhalents and I believe those are the only ones worth doing... if that.
However I had a friend who tried huffing petrol and liked it apart from an annoying ring. I believe that if you have the money there are better things to do then chroming.