I'm solely basing this on what we've seen released thus far for the Rebels and Imperials.
Republic:
Commander:
1. Anakin Skywalker
2. Obi-Wan Kenobi
3. Mace Windu
4. Yoda
5. Generic Commander, likely a Clone Commander since that would be like what we see with what has come out so far but a generic Jedi Knight might work too.
Operative:
1. Ahsoka Tano
2. Captain Rex, there is a distinct question of how they will handle the many Clone Commanders so this is just a best guess with the Jedi main characters serving as Commanders
Corps:
1. Phase 1 Clone Troopers
2. Phase 2 Clone Troopers
3. Cold Assault Clone Troopers
Special Forces:
1. ARC Troopers
2. ARC Trooper Strike Team
3. Jedi Knights/Jedi Sentinels, or an unlikely deep cut would be the Clone Assassins
4. Clone Commandos, they lend themselves to Infiltrate as well as having a configure weapon
Support:
1. AT-RT
3. Blurgg Riders (Twi'lek)
Heavy:
1. TX-130 Saber Tank
2. ???, lots of stuff is too large to fit here and a Naboo type speeder from TPM would likely just feel like a lesser TX-130. One of the proto walkers from Legends might work as a psuedo AT-ST I guess
CIS:
Commander:
1. Count Dooku
2. General Grevious
3. Assaj Ventress
4. Darth Maul, yes he never worked for the CIS but I could still see him being lumped in here like he will be in X-Wing
5. T-Series Tactical Droid (Generic Commander)
Operative:
1. Cad Bane
2. Savage Opress
Corps:
1. B1 Battle Droids
2. B2 Battle Droids
3. ???
Special Forces:
1. BX Droid Commandos
2. BX Droid Commandos Strike Team
3. IG-100 Magnaguard Droids
4. Geonosian Warrior Caste, they could have Jump 1 and be very mobile forces D-Wing Droids could work too
Support:
1. STAP Speeders
2. Destroyer Droid
3. Dwarf Spider Droid or to keep a mounted cavalry unit then Geonosian Picador Riders
Heavy:
1. AAT
2. Tank Droid




