Is one brand better than another? I was looking at Crawford.
Its been a while since I looked at this but there are definitely differences.
The crawford is good in that is integrates a coolant line so you dont get gunk buildup in the cold. Others will have this feature as well.
I seem to recall that the grimspeed AOS has some concerns with oil sloshing up the filler neck, or some other potentially dangerous issue.
Then there are AOS the integrate a physical medium to allow the oil to collect on, like a steel wool. I don't know if its worth it, or necessary, but its at least a feature.
Ultimately there are pretty simple devices. If you can weld, you can make one. So I would look more towards fitment and, frankly, looks than most of the other stuff. So with that being said, the Crawford is a good piece, just may be more expensive than a similarly performing alternative. But its a complete and proven package that'll bolt right in without much hassle.