For me, I tend to focus on where I’m lacking and try an polish that area down as best I can. When I started leveling heroes, I had a tendency to prioritize support heroes, then I went with AoE heroes, then I went with snipers/DoT heroes. Now that I have a pretty deep roster of 5* heroes, I tend to focus on which colors were lacking what.
I noticed my green heroes had nothing but support (Alby/Tarlak/Evelyn) so I maxed Kingston and then Gregorian to compensate for their lack of destructive power.
For my blues, I recently maxed Aegir over Richard because I had nothing but offensive blues.
For yellow, I have always had a nice mix of heroes in the way of utility, offense and support (Delilah, Inari, Joon, Drake and Ranvir). Right now I recently pulled Neith, so I may max her, but I also have Leonidas to consider as well as Justice and Vivica… decisions, decisions.
For my reds, that is a current issue. I have almost all 5* utility reds in Zimkitha, Red Hood and Ares while the other two are Marjana and Khagan. I have the rings to max either Anzogh (who is a combo support/offensive hero) Cap’ Kestrel (a fast, partial AoE hero), the recently acquired QoH (a combo support/partial AoE hero) or I could wait for Jean Francois, but he’s another red utility hero… so I’m not too sure. I’m not sure why I’ve decided to play it super safe with my red heroes, but that is the route I chose to take.
Finally, my purple heroes are almost all offensive because there really aren’t any 5* purple utility heroes other than Aeron and Kunchen (the latter of which I have maxed), so I chose those heroes based off of what they add to my other colors (I usually go 3-2 when raiding). I have Seshat (sniper), Victor (DoT, def buff), Thoth-Amun (partial AoE) and Kunchen (cleanse, healer and def down).
Since my roster is so much deeper now than it was before, I have recently started leveling my troops. Currently I have both versions of all the mana/crit 4* troops, and I’m trying to get them to level 23 as quickly as possible, though the grind seems impossible.