MIMF

Hi everybody
I would be happy if you could explain what features are important when choosing an amp for testing pickups during setups and new builds, furthermore it would be great if you'll recommend specific models. Thank you.

Roland Micro Cube....fits on any bench and will be all you need.

That depends on what you mean by "testing pickups". Anything is fine if all you are interested in is seeing that they work.
If you need to hear how they sound, the answer is more complicated.

Yes, I need to hear how they sound.

That is a very difficult question.
There are too many factors influencing pickup tones, to truly hear what each and every type sounds like.

I suppose the quick answer would be to buy the best tube amp you can afford. Something with a 10 or 12 inch speaker.
Anywhere from 15 to 60 watts, and with 2 channels if possible.
This seems to be the configuration a lot of gig players go with.
A tube amp will give you a more honest read than any modelling amp, in my opinion.
Fender amps seem to be the average cost, clean sounding amps, but there are many brands out there.

When I build guitars, I go for a clean sound. Clean is more difficult than dirty. Dirt can be accomplished easily with a stomp box.
Again, this is only my opinion.

There's probably a decent amp for every budget. If you want to save a bit you'll have to look for vintage amps that are currently out of fashion. The perennial favorites will always be fetching top dollar.

A used Genz-Benz Shenandoah 85 and a kitted Fender Deluxe...less than $300 for each. The G-B is for acoustic installs (takes some time to get things right on some pickup systems) and sussing out mag pup issues, while the Deluxe is decent for the stuff that normally gets plugged in. Had a Cube on the bench - not enough when folks are paying you for your time.

Dang, all I have is a pignose amp and an amplug vox 18.

Thank you very much for your answers, I appreciate it.