trinityamps.com

i'd love to see a lightning 5w. i'm looking to do a new low watt build soon, since my 18w is overkill for my bedroom playing in my apartment. i'm getting frustrated, i can't ever play the amp at a decent toneful volume.

Which is better, class A or class AB?
From a guitar amplification standpoint, neither class of operation is necessarily better, they are just different. You shouldn't get too hung up on the "class A" designation, because most of the push-pull amplifiers that are supposed to be class A aren't really class A at all, they are just cathode-biased, non-negative feedback class AB amplifiers. Operating class is not the reason for the tonal differences between these amplifiers.
The cathode biasing and lack of negative feedback is one of the main differences between the Vox clones and the Marshall/Fender style stuff. The typical Marshalls and Fenders used a fixed-bias output stage with negative feedback from the output back to the phase inverter input, while the Vox clones use a cathode-biased output stage and no global negative feedback. In addition, the output tubes and preamp stage/phase inverter configurations contribute greatly to the tonal signature of these amplifiers.

Which one to buy?

The bottom line is this: don't worry about whether an amp is "class A" or not. If you are interested in details, find out if it is cathode-biased or fixed-biased, and whether is uses global negative feedback or not, whether it uses a pentode, triode, or ultralinear output stage, and what type of output tubes are used. These parameters will give an idea of the "feel" of the amp, but in the end, you still must play the amp and use your ears to tell you which one is best suited for your playing style. Don't make a decision based on technical specs alone, you may miss out on a great-sounding amplifier!