Can you give us an idea of budget?
What kind of sound do you like? Fast & detailed (Pioneers lean this way) or more on the full-bodied warmer (Yamaha) side? My memory of the Mordaunt Shorts are that they could veer towards brightness, so might need a Yammy to take the edge off. I can't be too confident about this though as it was a few years ago that I heard the MS.
Now is an excellent time to buy an AVR with new models from Yamaha & Pioneer arriving in the shops, there are some cracking deals around. One of the best deals I've seen, for example is the successor to my AVR, the Pioneer Sc-2022 at just £400 (albeit an ex-demo example). That really is a lot of metal & excellent sound SQ for the money.
There are bargains to be had with Onkyos and Arcams too, so it depends what you like. Synergy is as important as budget though, so although it's a faff, it's really worth testing your speakers with any amp you have in mind...or thoroughly checking out the dealer's returns policy first! Even if you had to spend a little more than some crazy Internet deal to get a decent demo, it's worth it, as you'll have many years to rue a hasty decision!