I got some Dalmar lightweight air cooled ones - they were expensive but they are really good. I've noticed the legs are a lot cooler when I take the boots off and they fit well and don't slip.
Bog-standard brushing boots - Woof Wear every time. Not for XC though as I prefer to have ones with a tendon guard in - I'd go for some air-cooled ones like the Dalmars/Premier/Tri-Zone.
Are Woof better than they used to be. The pad on the inside of the leg used to be covered with a Vinyl that split and fell apart but that was xx years ago.