The optional gameplay to temporally play as a side character during missions just like they did for chop
I can see hood safari mission in gta v would had have Lamar be playable since his dialogue escaping together with either Franklin or Trevor
GTA VCS: Sharks due of their unlimited resources in farewell to arms and they control most of the empire buildings in the start of the game cannonically, they also kill full armor and health Vic in few rounds from their car
GTA VC: Vercetti gang because it's an upgrade to Diaz's gang with better leadership from Tommy and his ownership of all the bussinesses in vice city given he also has allies from cubans, bikers and Ken Rosenberg who is a lawyer
GTA SA: The SF traids are the most popular throughout the entire state of san andreas given they have military grade resources like chopper, bugs, minigun, fast cars and casino in LV, Woozie even sends many of the traids to aid CJ take back Madd Dog's mansion taken over by a high ranking Vago
GTA LCS: The silicians even if they operate outside from LC, they have many resources and they are good manipulators even having the mayor of LC through the forellis in their pocket and cause the main conflict for Salvatore and Tony
GTA III: The columbian cartel since how their spank product has high demand and have the traids and yardies even the leones after Salvatore fell out and thought Maria was cheating on him with Claude, their new leader Catalina is ruthless and runs the cartel with iron fist and the gang becomes Claude's number 1 enemy
GTA IV: The Gravelli Crime Family because they are the top mafiaso crime family in the comission and John Gravelli has loyal men who do anything for him, they also have government contact through ULP agency and locate and finds Darko who isn't even in USA
GTA V: Madrazo Cartel because as far as little screentime each gangs have in gta v Martin is known for never being convicted and has many coke dealer associates even has vast wealth and heavy guns