Seems like this question gets asked quite frequently.
What my man edwardw said is 100% true. I also own both and both have worked flawlessly for me. I probably have 15-20 flights on each. I will add the following.
1) Smallest tube RRC2 will fit into is 38mm coupler. MAWD will fit a 24mm tube but I'm not sure a 9V battery will. If you want to fly your altimeter in small rockets, this is a consideration.
2) The manual for both are on the mfgrs' web sites. Check them out and get an idea for the different features and how they would be used by you.
3) I like MAWD feature of reporting last altitude recorded on power-up. Also, advertises up to 3 seconds of power interruption. I don't know if this is really true, but if it is, that is a very excellent feature.
4) I like the RRC2 feature of more substantial connector terminals. The RRC2 seems more rugged all-around, but I've never broken either. I have put my RRC2 in the water twice and it is no worse for the wear.
5) I would buy the RRC2X instead of RRC2 because a) the battery terminals seem to be a failure point due to too much stress on the PCB and corrosion; b) I might like to mount the battery a little further away from, underneath, or beside the altimeter.
I can't say which I like better. Look at the features and see if anything stands out for you.