A bit of both depending upon their ability to produce 'Mechs/acquire 'Mechs. Where the OA forces were a hodgepog of whatever they could acquire/were gifted by House Davion (since they had no capability of manufacturing their own), both the TC and the RMR produced their own homegrown designs and were able to field at least companies of the same design.
Once the periphery was suppressed, their military forces were disbanded for much of the SL era. Once they were given permission to rebuild a limited (official) military, we go back to the reunification era status where their military forces depended heavily upon their ability to manufacture/acquire 'Mechs. It should be noted that a lot of the 'Mechs they acquired in secret during the military buildup came from Amaris who acquired them from numerous different sources and as a result got a mixed bag of 'Mechs.