Rest assured, either speaker is a great buy, and both the M40 and M22 will outshine anything within $300 of the price. As for which you'd like better, it depends on your musical tastes and listening habits.
If you're primarily into jazz or classical, the M22 is the way to go. If you like a warmer sound, or listen to pop and dance music, the M40 will likely be the better buy.
Something you can also try, that will not cost you all that much...order both and just keep the speaker that you prefer. You'll have to cover shipping, but I'd look at that as paying for the chance to audition speakers on your equipment, with your music, and in your room...a small price to pay for a long-term investment.
