Do you even know how loud 100w amps are.
I have a 75W Line6 amp and i cant play it in my house cause its to loud
Ew, line6, no offense.
First off, if you want to play concerts you're gonna need something good, which is a head and cab combo.
Some good brands are Mesa, Peavy, Fender and Marshall(in some cases)
The guitarists in my band use a peavy 5150 and the other uses another peavy head, but I can't remember the type.
The best kind of Combo amps however are probably Fender Vox's. They're loud and have a great crisp sound, however, your guitar and it's pickups play a big role as well.
I don't know how much you're willing to spend, but I'd recommend a Mesa(single, double or triple rectifier)Boogie head. They're some of the best heads you can get. Peavy is next, 5150s, or 6505+ are great heads too. Also Marshall JCM9000's are good heads. Probably the best in the Marshall Family. But if you can't afford those, buy a Fender Vox, but I'd highly recommend saving up for Head and Cab.
Btw, Cab's don't make much of a difference in sound, A marshall cab will do just fine. Also, get a Tube head. You'll know it's a tube amp if it has a standby switch.
Could you tell me what music you play and what guitar you have?
I might not know a lot about guitars cause I'm a bass player mainly, but I play guitar also.