Speaking as a technician, there's only two brands that I will consider as safe viable, reliable devices.
Xtar and Opus.
Both are very well built and highly regulated, and have been tested (with supporting videos, and proper test equipment) on YouTube.
The biggest difference (obvious to the laymen anyways) is that the better of the Opus options incorporates temperature monitoring as well as a fan that only kicks in once certain components get above their set range for temp.
The Xtar VC4 is probably the best all around value, but for maximum options (and in my opinion, added value safety features) the Cadillac would be the Opus BT-3400.
I'm in the same boat as you here... I just haven't decided my price point is all. lol
One can be had for around $25 (give or take) and the other's about $50 (give or take).
display and abilities are much more in depth and technical on the Opus however, so you can easily guess my automatic tendency.