My own press has a distance of six and a quarter inches between the cross rails of the bridge. I have had problems with smaller presses not being able to fit some automotive transmissions between the cross rails. It is a nice feature if the bridge can be lifted with a winch to reposition the pins, my own press does not have this, but my next press will have it. My press is supposed to be rated at fifty tons, I think that is overkill and I am sure that twenty tons would be just fine. My press has two pedals, one when pumped moved the ram quickly but doesnt have as much strength, the other is like using a lower gear, it moves the ram slowly but has tremendous power.
Since I drive a KX500 you can note that I like to go a little overboard, so my opinion is to buy the biggest ,strongest press within your budget. You will probabaly own this for the rest of your life, so get a good one, your heirs will appreciate it.
John