For concealed carry, I also have opted for the Kahr PM9. Very concealable, lightweight, good sights, and very good trigger/accuracy. I definitely would not consider the Kahr to be a 'budget brand,' they are very good quality, and of course, their prices that reflect that quality.
I also have an M&Pc and like it ok. It does have very comfortable ergonomics, and good capacity, but a lousy trigger, and therefore so-so accuracy. I know I could do the trigger upgrade that makes it a better shooter, but it ticks me off that it's so poor from the factory.
I've got a good carry holster for the M&Pc, but after carrying the PM9, it's hard to love carrying the M&Pc. The extra round count is nice, but again, for conceal, it's hard to beat the PM9. I also shoot the smaller PM9 better than the M&Pc, so that's also a big factor in what I'm going to carry.
The MK9 is a nice gun, but can see where it would not be much fun for carry; too heavy compared to other options in 9mm/.45acp. Just my opinion.