I've used a Marshall amp before I switched to Vox and I only did that because the guitar shop near me was all out of Marshalls. I thought I'd regret it, but I actually found Vox to be more customizable and with a much cleaner sound. And now I just love it to death. I've never used VT15 (I have one of the AC30 clones), but Vox is a great brand and I think you can't go wrong with it. Do a bit more reasearch on the model (personally I'd go with something in the 30s range, they have more oomph).
Don't cry, don't regret and don't blame
Weak find the whip, willing find freedom
Towards the sun, carry your name
In warm hands you are given
Ask the wind for the way
Uncertainty's gone, your path will unravel
Accept all as it is and do not blame
God or the Devil
~Born to Live - Mavrik~