Depends on yer bum.
I use a Sargent and did 842 miles in a day recently (Iron Butt Association) with no real issues. Others find them uncomfortable.
As they're easily swapped over, see if someone would lend you one for a few hours and try it out.
There's always the Airhawk. It will work once you get the volume of air right for you. Having said that, I no longer use it on my 1200 since buying a Sargent. Very happy with that, 1800 miles in just over 3 days, no problem But as said previously not guaranteed to work for everyone.
I suspect only a few people will have tried both and as Comberjohn says, it's down to your bum. Personally, I'm very happy with the Kahedo I've had for around 7 years and have done >400 mile days on it in comfort.