42" is what I built mine to. Very comfortable height when doing alot of reloading while standing. I find if the bench is too low, then you will bend more to pull the handle of the press. Thats not a big deal if you load very small quantities, but the more you do it, the more sore you will be after a loading session from bending.
My benchtop is made from two sheets of 3/4" ply glued and screwed together, with a 4" lip for mounting my presses. I now have two mounted on there, and cabinets built on top with doors covering it all. I should get some new photos for you, but these are what I have.
I used tapcon's to bolt a frame to the wall, then built the whole bench using pocket screws. The thing is a tank, no motion whatsoever. It is the best bench I have ever had the pleasure to use, no wobble or motion.
Here is one more tip. Don't cheap out. Spend the extra few dollars on materiels and you will have a finished product that will last a lifetime if you build it right.