15? crikey!
these are in no order, by the way...
engl savage se or se (have the savage se; both are great for a wide range of tones and would be my choice if i could only have one amp)
brunetti xlr-evo
cornford
soldano (only tried the avenger; i assume the slo is even slightly nicer)
bogner ecstacy
cornell
thd flexi 50
mesa roadking
splawn (haven't tried; i'm basing this on soundclips, unfortunately)
diezel
vht
obviously vintage fenders, marshalls, voxes would be cool too... (i'll make those my #12-15)
i'm not sure i need 15 amps, haha. also i've cheated above and not always listed models as I haven't necessarily tried all the models by a certain brand... also, there's a bunch of boutique brands which i've never been able to try... carr, fuchs, /13, mojave etc. etc. etc. and while I'm sure they're great, I can't really say they're on my list without trying them (i make an exception for the splawn, as i play a lot of 80s rock and metal, and it's, from all i hear, aimed at that). :)