I would go for the MSP5. I owen them and a very happy camper. Do a search here on GS. You have to learn them as any monitor, so be ready to do that. I have a friend who has the Adam A7x and we both agree that apart from more bass on the A7 (bigger cone), the difference is not much, maybe a better stereo field on the A7 and thats about it. I must add that both these monitors (A7/MSP5) are on the flat side of the monitor world! There are other monitors that are not so flat, which is not the case of these two. The quality, as in most if not all of Yamaha products is great, the MSP5 is a "tank" its self. Sound wise It´s mid-high with clear definition, the bass section is a bit weak but well enough to mix with, unless you have a big control room. Plenty of power for such a small monitor, this thing will "spit" air at you if you dont watch out.
As said, if you want a fancy sounding monitor look else where, if you want "flat" mid sounding monitor, go MSP5. Good luck!