Welcome to Chordie, Donnie ...
The 15w Fender Bassbreaker is a terrific tube amp ... can't go wrong. A 15w is a very common size to go with for a practice or studio amp, and will give you plenty of volume if you're jamming with some friends, but doesn't have to be turned up overly loud to get good tone. Here's a simple trick with a tube amp to get the crunch you're looking for, without cranking it too loud:
1) Start with your "Master" volume at "0"
2) Set the "Structure" knob at "Low" or "Med"
3) Set the "Gain" knob up a fair bit (halfway or more, depending on how much distortion you want).
4) Then simply raise the "Master" to the volume you want, and you'll find there's lots of crunch at a household-friendly volume.
The layman's / simplified reason this works, is that the "Gain" knob amplifies the signal from your guitar before it hits the power tubes; this is where the distortion comes from. The Master Volume then simply controls how much audible volume comes out through your speaker. You've obviously done a fair bit of research already (judging from your comments) and a tube amp is definitely the right way to go (IMHO). A couple other low-power tube amps (with an effects loop) that you might consider are:
1) Traynor YGL1
2) Hughes & Kettner TM18
Both of these amps have a separate "Gain" knob to enable the little trick mentioned. Hard to go wrong with your first choice, though. The Fender Bassbreaker is a really great amp. I certainly hope this is helpful, and some other Chordians will no doubt pitch in.
ACOUSTICS: Cordoba D10-CE / LaPatrie "Concert" / Takamine GD30CE-12 / Norman ST30
ELECTRICS: EP Les Paul Custom Pro / Gretsch Streamliner G2420T / EP Thunderbird Pro IV bass
AMPS: Traynor YCS50 / Peavey "TF" VK212 / Traynor AM150T / Fender Rumble 150
EFFECTS: Boss ME-80 Multi-effects / Ibanez WD7 wah / Grand Orbiter V3 Phaser