I like stuff that's uncomplicated with digital or computerized failure points whenever possible.
For a booster I bought a fairly basic Duralast unit from AutoZone, and it's been fine.
Battery tenders: the Schumacher units have been better than others, but I also have a Duralast unit that's been fine. Around $40, IIRC.
Had a Black & Decker tender that failed after a few years.