Don't buy the "big box" ones - most still use oldschool lead acid batteries. Yeah, they work, but you MUST recharge them after every use in very short order otherwise the little lead acid sealed batteries in them die a premature death very quickly.
As for bad reviews on many others - I'm pretty sure a lot of bad experiences are user error - people just don't know how to use something or have unrealistic expectations - I once saw someone complain that one of these things "died in 10 minutes running the space heater in my tent!"...FFS some people are just stupid.
