The original season was done by Gonzo, and while I love the plot it follows that is all thanks to the novels. FMP! Fumoffu and FMP! TSR were done by KyoAni, and are far better done.
I enjoyed them all for their mixture of realism with sci-fi elements. The mechs are slightly more believable than many shows because of their size, and I like this as well.
I find Fumoffu hilarious personally because it's basically a slice of life show with a weaponry/combat twist to it. I don't really know how to explain it all and do the show justice, it just sort of works.