which would you recommend because there about the same price

 I have no experience  with the YHM hand guards but I do own a set of MI 2 piece handguards and they are great.  Mine have a tight fit and there is no movement.   You do need to use a handguard removal tool to take them off and on.    The rails are also marked whereas YHM handguards aren't  if that makes a differance to you.

   YHM's quality is second to none and I don't think you would be dissapointed  with either handguard.

   

no im talking about the freefloat versions

I would say give the MI's a whirl...

No need to completely disassemble the barrel/FSB, etc.
I believe the MI has better anti-rotation than the YHM.

That said, I just purchased a 12" YHM FF...(thanks Teknic!)
too impatient to wait for MI's rifle-length FF,
and I wanted to try my hand at working on my upper

It's a really nice piece, more affordable, and I'm sure it will work fine.
(but I do have a few ideas if it starts to rotate...)