Oh, man. I love low-powered amps! I could talk about small amp tone all day...
A 5E3 is on my hit list.... I'll probably build one like Dub did. I have a vintage SF Deluxe Reverb, but that's a very different circuit from the 5E3.
The aforementioned SF DR is 22 watts and my handwired JTM 45 clone is 30ish watts. Everything else I have is less.
Here are the ones I use regularly:
Silverface Fender Vibro Champ - 8 or so watts... This amp totally kills for small bar gigs (and yes it keeps up with a drummer)
Silverface Fender Princetons - I have two, a 68 reverb and a 69 non-reverb - totally different beasts. The PR reverb breaks up ALOT more due to the extra gain stage. The non-reverb stays clean to 10. Use these for larger bars - or if I am not using a guitar mic.
Marshall 2061X handwired reissue head - 20 watts... this is my new favorite amp for rock and roll in decent sized venues. It's loud with the 4-10 cab... real loud. I use one of my attenuators on it too.
Some I use less regularly:
A Champ clone made for me by a friend 8 watts with more of a Marshall breakup. Basically a Champ with a Marshall tone stack.
Epiphone Electra.... 12 watts - identical to the Gibson Minuteman. Great blues rock amp. Really screams. And I built one of my attenuators into it so it's easy to dime it.
Marshall JTM1 head - 1 watt... which is still pretty loud at home. This is a great living room practice rig. Sounds like a JTM should but without the hearing loss.