This is honestly a matter of personal preference. You want a seat that is snug, yet comfortable. I currently have an FIA rated MOMO seat. Many racers prefer the aluminum shell offerings from Kirkey, Ultrashield, etc. The road race versions from those guys are much more comfortable than they look. The best advice I can offer is to go to the track and ask to sit in different peoples race cars. After the puzzled looks, explain that you are trying on some seats before buying one, and most everyone will be happy to help.
Jim