I've had both AP SMX+ and Sidi vert II.
I can tell you that if you are tracking your bike, AP is by far a better boot. BUT, if you're looking for a little more protection than some docmartins, then the Sidi boots are excellent. They are far more comfortable than the SMX+, and they provide good protection for most riders. My boots have an ankle guard on both sides and I like the fact that the outside edge is removeable incase I need to replace them.
Here's my lowdown, hope it helps you out some.....
Pro's - Excellent boot for the buck, lots of protection, great for trackdays w/ leathers, feet stay warm in cold weather, cushioned like a tennis shoe.
Con's - Not well suited for daily riding, hard to 'feel' the pedals (I had a hard time getting my toe under the shifter and I locked up the rear brake without even knowing it), very bulky, must tuck jeans inside boot to keep from rubbing calfs raw, harder to get in and out of boots, feet get really warm on long rides.
Pro's - Lightweight with good protection, easy to get in and out, fits under most jean pant legs. Could be used for mild trackdays, replaceable toe/ankle sliders, very conforming to your feet, breathes well, easy to 'feel' the pedals, toe goes under shifter with no problems.
Con's - Not as armored as the SMX, some leathers will not tuck inside boot, does not keep feet warm in cold weather, squeeks from time to time (but so do supertech's after time), screws 'can' back out, sizes are ODD (I'm a 10.5, and I wear a 43 Sidi, go figure)