I LOVE my Speedplay Frogs. very easy to get in and out of, and also very kind to your knees and or ankles if you have problems with either. I tried SPD before frogs and found them very different. They were difficult to get in/out of and my knees hated them because they don't have much float (more float = more freedom for your knee/ankle to move around as they need do while still being attached to the bike). Some people need more float than others. My SPD pedals may have come from a bad batch, but I've not looked back since moving to Frogs. The pedal is larger than my SPD pedals were.
Whichever shoes you purchase, outside of fitting well I highly recommend more of a rubbery sole rather than hard plastic. Some mountain bike shoes have hard plastic soles where they contact the ground and that can get slippery in my experience. Not soft rubber, just not hard plastic. I had a big problem with this with my Bontrager shoes which are now relegated to spin class only - I strongly dislike the hard plastic surface.