1) Mantis gas is basically a piece of junk. Mine didn't last one season...the air intake is way too low and sucks in dirt resulting in blown engine. Poor design. Not recommended.
2) The Black and Decker cultivator (battery powered) recommended on here is basically useless for weeds. Not recommended.
3) Recommended: 4 cycle engines w/adequate hp, never, ever use ethanol fuels in them and always use fresh gas or treated gas. They last a long time, easy to start, very effective, and very efficient.