I have the line 6 spider myself. I have to say I really am pleased with it. The array of effects are nice but its the celestion speaker that really sold me. Once you get use to the settings its fairly easy for me to get the tone i want. If you have been playing for fifteen years though I easily see how you could be looking for something different.
The first things you would want to decide is how dedicated your going to be to your music, and thus how much you want to spend on it. Also if you want a combo amp or a stack, if you go stack i would highly recommend the Vibro King by Fender.
What i would do is figure out what guitar you want, and then play it on the amps at your music store to see which one meets the tones your looking for. Also c=see who your favorite artists are, what tones you want to try to catch, see what they use. john Mayer for instance uses the Vibro King I mentioned earlier. I hope that helps.
Infinite-T I was wondering which tube screamer you went with? Ibanez has about 3 or 4 of them now between the ts9 and ts808 and t7 It gets pretty confusing. Do you have a recommendation?