Here are the things I'd want in a new bench:
1. The top is thick. I've used a solid-core door in my favorite bench, and it's not too thick. Thicker yet would even be better.
2. Leg levelers. My father-in-law showed me a way to level legs on a bench that I've used since then. You use a 2x4 to support the top, then attach 2x4 legs to each side of it. Then at the bottom, a 2x4 connecting the front and back leg sets, with slots cut in it so it can be adjusted to level the table. A pic showing what isn't easy to put in words:
3. Some sort of shelving apparatus above the bench. This might be something you'd attach to a wall, as I have done, but I've found such shelves to be godsends--they get stuff up and out of the way, reducing clutter, but making that stuff readily findable and available:
That pic shows my golf clubmaking setup, which has actually been converted now to reloading. But that little shelf, dumb as it may sound, is just terrific.
4. I want enough room on either side of my presses for whatever. At least six inches, a foot is better.
5. Room under the press for my legs, shelves, whatever. The pic of the bench above shows a shelf under the bench, but because of how the legs are set up, it's far enough back to stay out of the way of my legs, but still provides storage. The shelf is a piece of plywood set on 2x4 crosspieces run the long-way and set just above the bench levelers. That gives me room for toes. (You can see this better in the first pic above)
6. A way to attach the bench to the wall studs if it's up against a wall. The way the bench in the photo above is attached to the wall with angle irons. The bench is heavy (that solid-core door plus all the 2x4s plus the shelf plus the stuff on the shelf make it very stable, but I wanted something to keep it from pulling away from the wall if ever I put that kind of pressure on it.
7. A lot of benches are made at the height of a normal desk. Mine are at least 37 1/2 inches high. It's a comfortable height for standing at them and working, and I have a tall stool I sit at while reloading. A shorter, more standard-height desk I'd not be interested in. Might be worth making one at a standard height for those who want to sit at it in a chair, and allow for 2x4s to be used (laid on the side) to raise it 3 1/2 inches for those who wanted that.
8. Finally, even though my work area doesn't allow for it, if I were putting the bench in a corner, I'd like an "L" shape to it. With the short leg of the "L" on the right, It would be nice to have more room on my right for a press, extra stuff, whatever. Just being able to turn 90 degrees and have another complete work surface would be nice. I can imagine a "bolt-on" option for the extra leg of the "L" for those who'd want it.