The MMA and Veteran both have great value depending upon the battle. If the opponent has lower HP troops the MMA can wipe out most of them himself. But if the opponents are tougher then often the Vetran by virtue of carrying 250 troops has the extra power necessary to make a two wave fight into just one wave. Often I use the MMA whenever the guide recommends cavalry (even if I have to drop a few) and I seem to save a fair number of troops that way.
Having both an MMA and a Veteran I think is the best way to go and use the calculators to check the difference when using them. For myself, I had an MMA first and was very happy with that. Getting the Veteran later then gave me even more options and now I'd like another Veteran. Working on that...
Hope this helps
Sorry, but I've slept since then...
MMA is beast.
Here's my MMA Bandit Nest guide without cannons.
If you're willing to lose some Cavalry for not having a 3rd MMA or Major, the guide can be used as low as Level 36 and has significantly lower losses than classic Veteran guides!
or wait on refresh of a mma - if you can spare the time/patience for that )