all three are solid,well made pistols but there are differences.
balance: the standard cz75b/bd and ar-24 balance in the hand about the same. when fully loaded,these two are basically centrally balanced which some really like.
the MR BDE is different. it will have a balance a bit more bias towards the muzzle end. for some,this will make it better for faster,well aimed follow up shots and it should give better stability horizontally. in this respect it's similar to a cz sp-01,which is part of why that model is popular for some competitors.
your call.
grip: of the three,in my hands,the ar-24 feels the best. it's basically the same grip as the cz but it has the improvement that tanfoglio designed of having a deeper radius cut for the webbing of your hand. the side rubber grip panels(first ones used to be wood in black) are also one of the best i've ever felt on these kinds of pistols. it fills perfectly the void in the center of your hand and i like how it slims down towards the top and gives a thumb shelf too. the cz has this too but not as good as the ar-24 imo.
if you have smaller hands,forget about it,the MR DBE will be the winner for you.
both the ar-24 and the MR BDE will help you reach the DA pull a little bit better than the cz,because of the grip and the shape of the trigger. they will both also help you get a higher grip if that matters to you.
trigger: out of the box both the ar-24 and MR BDE have triggers that are a little better than the cz75b/bd. i felt the ar-24 had a bit better DA pull but the MR BDE a better SA pull. you can do a trigger job yourself on any of the three but both the MR BDE and ar-24 have a tanfoglio designed FPB that works with you insted of against you. both are also a bit easier to break down all the way. internally,the ar-24 is like a modern tanfoglio and the MR BDE is like the older tanfoglio ta-90 or there about,with the hammer spring along the back strap and safety/decocker on slide.
quality: all three are great quality but the MR BDE really lets you know you have a solid piece of steel in your hand. it weighs more and would be the best one if you had to pistol-whip someone for SD. the ar-24 has a forged,milled frame that the other two don't have and also has tighter clearances which was specifically requested by mark westrom(armalite) from sarsilmaz. i believe even many of the smaller parts on the ar-24 are forged too(if this matters to you,opinions vary),kind of like old-world craftmenship but with modern CNC machinery(mostly german and italian from my understanding).
your call.
after-market support: cz wins hands down without doubt,next the MR BDE,..last and certainly least the ar-24.
your call,you may not want anything for it anyway,..or you may want everything.
internet darling: cz wins here.
don't forget your manual-of-arms preference. if your coming of a 1911,you may prefer the cz75b or ar-24,..coming of a beretta 92fs you may prefer the MR BDE,..coming of decocker-only like most sigs you may prefer the cz75bd(a safety/decocker can work here too,just one extra move,turn safety off and GTG).
i don't think you can loose with any three as long as it works well for you but if you want,lets say,night sights or most anything else for the ar-24,good luck with that. i'm sure there're holsters that will work though.
hope this helps.