Well I voted 4-6 .

I tend do army building as a sorta ongoing liegeverse story/lore-fiction....

G1 - A swarm of insecticons I have 4 sets at the moment plus 1 e hobby version so 5 sets in total. Of course the Seekers, cassettrons, the ZFairlady etc, etc. I will include in this the G1 homage for later versions of the same characters (seekers, et al) - Generations/Classics, Baymovieverse, Animated, etc.
Energon - the 4 terrorcons gets 3 subordinates at least each ( serves as clones) I have yet to complete this - energon ravage and insecticon just dont come around too often (read: cheaply priced)

Cybertron - for army building - Unicron tanks - which I have 7 as of the moment... and a couple of Scrapmetals - 8 so far....more will be added to these two since I am making and army of em - in liegeverse these are part Unicron's Horde (including the Energon Terrorcons)

Straight repaint ... if I like it, Ill buy it as long as it's a different character altogether - but if it's just a "stealth", "Powerup", "Urban style", etc recolor of the same character... I'll skip.