If you just want some of the best and toughest without concern for price, then I'd say go with KAC. I'd throw a 99051 in black on the front with a 300m regular or micro rear. The 300m micro rear is a good bit less expensive retail than a regular 300m, but either can be had for a relatively decent price if you're patient and keep an eye on the EE. KAC does make some fine sights, and they are are pretty much bombproof... but compared to other brands they are definitely a bit pricey.
Otherwise, there is nothing wrong with a set of MBUS or MBUS Pros; they are quite good sights for the money. Being practical, it doesn't make a lot of sense to spend $250-$300 for a set of KAC BUIS that you're likely to zero and then never use again. Of course, BRD and "practical" doesn't always go hand in hand.
Besides, KAC sights turn boys into men and men into great bearded Norse gods of war. Also may cause women to spontaneously become pregnant. That's the rumor, anyway. More than one woman has been overheard in a hospital delivery room yelling at her husband, "Damn you and your KAC! This is all your fault!" So, I'm pretty sure it's true.