I agree with Dr. Dude, Aaron. For a gas powered portable one, the best one is one that has been Grooved!
As resident Dr. Obvious, obviously the gas powered one will run rain or shine, day or night. Run time will increase a LOT if the carb. is Grooved. You should also do the spark plug gap increase, and look at the new info messages here in the forum, on Nano-coated copper wire added to the plug wire, courtesy of Vernie!
solar is another good option too, but I don't have good info on which is best. A separate question is- how much electrical power do you need, to run what, for how long. Camping can mean anything from backpacking in to a spot, to taking the truck out ( Groove that too!) to the lake for a weekend of camping. Then there are the RV'er's and their rigs and generators. (Groove the RV too, if it's gas!)
You won't bring a gas generator in by backpack (will you?
) but there are lots of folks using small solar panel setups on their backpacks today. There do exist ($$) small portable Rocket Stoves that have a thermo-electric generator incorporated to charge a cell phone, etc. while you cook using wood twigs.
I could go on and on- but the question remains one of needs and use.
But if it burns gasoline, the Groove is definitely the answer!
Tracy G