I like the Corbin, but they are notorious for having small difficulties in getting their seat to fit whatever bike its made for.
My favorite though is the Russell Day Long. On my first R3T, I went through the stock seat, the Long Haul seat, a Corbin, and finally the Russell. The Russell is custom made to your weight and measurements. Every time I buy a touring or sport touring bike I have them build me a seat. When I bought my second R3T last year, I ordered the Russell seat concurrent with the purchase of the bike. I knew I wanted it.
The Russell workmanship is excellent. I prefer full leather, but they also offer vinyl options. Guys who weigh more than about 245 pounds are also advised to add the heavy duty spring set (built into the seat).
I've had 5 or 6 Sargent custom seats, 4 or 5 Corbins, assorted stock, gel, long haul, etc., but nothing beats the Russell if you sit in the pocket as advised in their instructions. The last four aftermarket seats I've bought have all been Russells.