I love all the models and everything about the company and the customer care of its distributors.
You would think by my signature that my favorite model is the Corvette, but honestly, I actually think the NT Thumb is the quintessential Warwick representative model, and I have my sights set on a CS version... That model is so uniquely Warwick in sound and looks - very sexy shape and size. I really like the offset pickups on the 5-string model, as they really enhance the look and the growl. To me, the Thumb is the pinnacle of bass guitar, period!
The Streamer seems to appear the most in the spotlight with big name players, and I love the tone people like Stu Zender, P-Nut, and Dirk Lance were getting with theirs. Great bass, but it doesn't have the "signature" look because it is based off the Spector, plus a lot of Streamers are made from various types of Maple, whereas another signature of Warwick is the more exotic woods like Bubinga, Ovangkol, and Wenge - commonly favored for Thumb basses.
10 years ago, before I was a Warwick fan, the only model I really was aware of was the Dolphin - it was a unique, boutique "signature" instrument and I thought it was the only model that Warwick made

The Dolphin is still an amazing instrument, but my tastes have become more "traditional," so the Corvettes are a nice, sleek and sporty, and affordable instrument to start me off, and the Thumb will be my "prize" model once I can afford a CS version.
As far as ranking goes for me:
1st = Thumb
2nd = Corvette
3rd = Streamer
But they ALL beat anything by any other company, IMHO!