MPA chassis is the most popular and allows for a great deal of customization. Manners stock does not. If you were to take a shooting fundamentals class, or do a lot of competitive shooting where you might want to raise/lower cheek, or adjust the buttpad from Prone to Offhand shooting in the middle of a CoF, MPA would be the winner.
If you like the looks of Manners, which looks great... then that's that.
![Smile :) :)](data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7)
If you were trying to find something light to walk around the fields and kill squirrels, then Manners would also fit the bill. I wouldn't buy a competition chassis, and haul that extra 3-4 lbs of weight unless I meant to do some competitions.
I have a KRG Bravo right now in my setup for my Tikka. It's a great all around stock, light enough to carry it, stable enough for multitude of shooting, but I am looking to buy something like the MPA or MDT for more customization for competition shooting.