If cost & comfort are a premium, get a used seat. Stock used seats can be surprisingly comfortable even if they were broken in by someone else.
Mean City Cycles do great customizing of seats & they are not expensive.
I have always gone with new Corbin's because I like their looks & "eventual comfort", because that 1st 1K miles or so are tough - but worth it.

 

I love my Danny gray solo seat. One of the better upgrades I've done. Not saying it's the best but it sure suits my tush just fine and way better than factory seat.

 

I've put lots of miles on a Mustang solo on my RK and have been very happy with it so I bought one for my Slim,

 

The general consensus on the Dyna site is the Mustang Wide Vintage wins by a large margin. Also available with a remove able driver's backrest. And you can add a removable pillion for the little lady...

 

I've been trying to get comfortable on a spring solo set-up for my Slim for ages - messed about with various seats, mounts and spring heights... eventually made up my own brackets... BUT

I still couldn't get comfy.

Eventually on a bit of a whim I bought a Deluxe seat off eBay and it's SOOOOooooo much better

It could do with a bit more padding, so as others have suggested I'll take it off to a bike seat specialist to tweak the padding.

Everyone's *** is different, but the Deluxe seat is (for me) a great starting point.

 

Mustang has a great solo seat