The main problem with French planes is that they only saw action during the Battle of France up to June 1940 and then briefly during Operation Torch. This means they have a limited number of scenarios they can be used in (two effectively). They wouldn't be very competitive in the MAs either, even in the EW MA with its much better 1941 era fighters and bombers.
The game needs at least one slow early war bomber for scenarios. Something from 1940/41; slow, poorly armoured and with rifle calibre guns for defence. Currently it is hard to run effective early war scenarios since the 1941 bombers we have outclass the 1940 fighters. You could have an He 111, G4M, Il-4, Wellington or SM-79. As an added bonus all of these were used as both torpedo bombers and level bombers. Any of these could sub for any of the others in a whole load of 1940-41 scenarios a lot more realistically than the Boston, B-25 or Ju 88 can.
The main lacks WRT fighters for scenarios are the Ki 43 and the Yaks 1, 3 and 7. The Ki 43 would be a fun ride even in the late war MA, slow and pathetically armed but it would out turn anything. The Yak-3 would be a fantastic LW MA ride. The Beaufighter has also a lot of scenario potential and would have a nice niche in the MA; a torpedo bomber with four Hispanos.
Planes like the B-29, A-26, Meteor, Me 410 and G 55 would do well in the LW MA but are more restricted scenario wise.