IMO, I'd get the Mordaunts. I haven't heard the Axiom towers, but I've compared the bookshelf speakers. The M3s have very good upper midrange, but the highs are just a bit too crisp, IMO, and low end is seriously lacking. The 902s have excellent midrange, good depth, and great highs and much better bass than the M3. The Mordaunts also look a lot nicer and feel better built to me, though the veneers on both are about the same. These guys will be perfect in a room that size, and for that size room, I'd go with 906s instead of 908s.
I installed a set of 904s, 905c and 903s with the 900 series 10" sub for a customer recently in a 15x18 room powered only by an Onkyo 601 and it filled the room more than adequately. I thought the 904s might not be enough, but they definitely did the trick. The sub wasn't impressive at all to me. I'd still say 906s though. He's extremely pleased with the setup.
DON'T buy their subs, this is MS's weak point. Look to SVS or HSU for sure; both are a better value for your money.