Manto are the lightest thing I've ever worn. It depends on your personal preference really.
I love my sprawl shorts for mma and thai. They've lasted forever as well, and are pretty much the original mma short. Only problem is they have big leg slits and are quite baggy so when you do ground work they're flopping all over the place and I feel like a highschool girl who's having the captain of the football team try to get to third base.
I have 2 pairs of manto shorts like these:
These are my favourite shorts just for them being incredibly simple and lightweight, and they have a great cut and fit. Only problem is I probably won't be throwing any high kicks or knees in them as they are slim fitting with minimal leg-slits and no stretchy bits.
The manto mma shorts might be better, but I can't comment on them.
I also have a pair of nogi shorts, and they're bloody great. They have a bit more room in them than the manto shorts, but again no leg slits. They have a lot more room to move and are a bit stretchy but probably not for thai. Great for mma or grappling though.
I didn't pay more than £20 for any of them and they've all lasted years.
The only other pair of shorts I'd maybe be interested in are the clinchgear ones. There were a few guys at my old gym who had them and they looked to sit really well on you. I also like the idea of having the flexibility of all those stretchy bits without them being floppy shorts that compromise the way they sit: