I like prawn's 4, and 5 if you remove the crossbar of the A. It should be associated with a subtext as it is rather abstract.
I can't get used to M's "target".
Some suggestions use a waveform, which often is not much aesthetically pleasing (try to smooth out a few spikes?).
Why a bear mascot? "Tom" is usually associated to cats (tomcat), so I would use that.
Maybe with that kind of face:
http://www.plushpaws.co.uk/user/products/large/26429.jpg





















