Out of 3 NIKON DSLR's mentioned which one should I go for?

Among these 3 which one is the best?

Nikon D5100
Nikon D7000
Nikon D90

I'm expecting a superior quality. I'm not a professional photographer but am interested in taking different shots. Your valuable suggestions please!

The "best" is probably the most expensive one (the D7000), but unless you know how to use it properly, it's probably wasted on you. If you're relatively inexperienced with DSLRs, the D5100 is a good place to start because it's aimed more at beginners and is a bit simpler to operate. The D90 is in the middle, where it has some more pro-level functions, but isn't quite as complicated.

When I was choosing DSLRs, I was also concerned about weight, because I like to have something I can carry around with me (the best camera is the one that's with you!). Generally as DSLRs get more advanced, they also get heavier.

Of the three, the D7000 is the newest and has the most features as well as is the most robust of the three.

The D5100 is an entry level camera, so does not have the environmental seals that the D90 and D7000 have and it can only auto-focus using AF-S lenses.

The D7000 is the newest of advanced bodied (like the D90) Nikon cameras

A few of my colleagues have adopted the D7000 as their backup APS-C sensored camera

Nikon d7000 is the superior of the lot, but d5100 is also good if you are no going to do any professional work.

The first thing that impressed me was the D7000's ability to focus in near darkness. I was astonished by this and wasn't expecting it. But the most impressive aspect of the camera is its dynamic range.