I started with the stock seat and found it unyielding and also too high for me (5'8", 28" inseam), so I bought a Rich's custom seat, w/ leather & stitching, and deeper/lower than the stock. After a few hundred miles I've found that the seat is very comfortable but the angle on the seat padding is slanted forward, so I slide towards the front/tank during the ride and am having to push back after some riding time, again and again. So, while in the parked position, I adjusted the seat to the "high" position and now the angle is just right, more level and comfortable. One key difference between the stock and most custom seats I've seen are: 1) the custom seat is wider in the back for more support room, and 2) the custom seat is usually "scooped" and broadened so that your butt fits into a wider "pocket" rather than riding on a flat surface. This distributes your weight better and if the underside is gel or flexible foam, you get a surface that adjust better to your shape and posture.
If you buy a custom seat and you find, after a few hundred miles, that you're really not sure it fits you, either go back to the maker and have it adjusted or sell it on this site for $ plus a stock seat and start over. The right fit is "priceless"!
See you on the highway,
Granger