My $.02:
1. Corbin: Stylish, hard as a church pew, too short, easily detachable passenger backrest is very handy.
2. Laam: Looks amazing, taller than stock, more leg room, 100% custom, very fairly priced, have heard/red excellent reviews regarding Laam's customer service.
3. Russell: Pure bliss and nirvana for your butt, too ugly to be put on a CB, pricey, 100% custom made for you. If money were no object, I'd buy this for trips and keep the stock saddle for around town.
4. K&H: Looks awesome! Fits style of CB beautifully, But $600+ for a off the rack, non-custom saddle? No thanks...
Also, I have borrowed a Air Hawk R from a friend and it seems to help considerably, however, still leaning towards a Laam.