Change it up between 30 and 45. I wouldn't go much higher than 45 degs. Stick mostly with the lower inclines so that your chest is still the primary mover.
At 45 degrees you are incorporating to much front delt. At 35 you are hitting your upper pecs harder and in addition will allow for more wieght use. LOL
that would be ideal. why not narrow down the possiblities by using what science says is optimal? then decide from the choices instead of trying everything for a while and deciding, on your own, that a bunch of it was crap. its a matter of not spinning your wheels.