This is a pretty good FJRkle to discuss because you can actually try different seat pad options before you decide by borrowing them from a bud on a group ride, or even getting generous offer like Rog made, but it's still a very subjective thing to evaluate--you either like something or you don't.
The other problem is it may take quite a while before you know how you'll like it. I've used a
BeadRider for a couple of years, and I like it a lot, but I was most of the way to Montana on my first trip with it before I knew that for sure. It allows some air to flow "under" you, but you don't really feel the air flow, which makes it good even when the temps are cooler, but the air flow keeps you from getting--without being too graphic--
sweaty. As much, anyway. So that alone increases long-term comfort. But I also like the way a little shifting on the seat actually gives you a sort of mini-massage. Oh ****, I just realized it's Friday. Maybe I should post this anonymously. But it's true, a little sliding back and forth feels kind of nice after some time in the saddle. It's lasted very well, too. I accidentally ordered two when I bought mine, and after I decided I liked it, decided to just keep the second. Figured it would fall apart like the "Auto Zone" kind, but it still seems good as new--bet it's got 20K miles on it. By the way, before I ordered it, I considered what OCFjr suggested, but when I saw how those things were made, I could see it'd come apart on the first day ride after I cut it up. You'd do as well just trying to balance marbles on your seat and ride on them.
I also have a sheepskin pad from Alaska Leather. It doesn't give much of ANY extra padding. Bought it to soften the hard-as-a-log Corbin seat that came with my first bike. Didn't help. Plus it made the "heat" issue, delicately covered above,
worse. Maybe after it cools in the fall I'll try it again. The seat on this bike is also a Corbin, but a LOT more comfortable than that first one. I finally traded that one straight across for a lot less expensive Sargent seat.
A friend with a BMW dual sport has an Air Hawk, which I tried on a short ride. It definitely offers good padding, and I bet it would be nice on a hard seat, but I don't know if it offers much or any relief from sweating and resulting chafing. It also adds more height than the others I've mentioned, if that's an issue for you, good or bad. But like all of these, easy to switch between bikes, or keep when you sell and replace what you ride. Of course, it would be kind of easy to have it walk away by surprise, if you're not careful. . .