Hello Tom,
I've had a bit of experience selling such amps when I was doing retail for 3 years and I also picked one up for myself. I do like a good modeling amp, and I believe the technology is pretty darn good.
Line 6, of course, was the first out of the block, but for my money I'd never own one; I've heard a few that sounded ok but they belonged to folks who replaced the original speakers with Celestions. Other than that I never liked the sound all that much and I am not a fan of digital displays on amplifiers (like on higher end Line 6 and Fenders),so I prefer modeling amps that just feature knobs rather than a ton of knobs and displays as well. Fender makes the Cybertwin and the smaller Cyberdeluxe which sound good, but give me a headache with the complicated controls. Most salespeople will try to sell you one of the Fenders for a few different reasons: A) lots of guitar players (who in this case happen to be salespeople as well) just go ga-ga anytime they hear the word Fender and won't consider anything else to be on par with it , wether it's true or not B) Fender has a program called Fender Dollars for salespeople; sell x dollar amount of Fender gear and get Y dollar amount to apply toward purchase of Fender products.
I could have had any amp I wanted at dealer cost but I put my money on the Vox Valvetronix, (1x12 version) which I really enjoy and get compliments on all the time. I also like the effects it has and it's real easy to use. I sold a few of those and always got thanked afterwards when I steered the customer towards it.
Having said that, I suggest that you go out and test a few of these amps yourself. Find what you like, your taste is likely different than mine and you may enjoy tweaking knobs more than I do.
Valentino