3* - SL I have literally 8 purple and green covers in queue and hes sitting at 2 yellow
4* - all retired 4*s that don't have 5 covers in any single color - theres about 6 in this boat... its realistic to expect to cover all the 4*s eventually as I'm covering all new ones with resources to spare, its just going to take a while. I can ensure the BH cover in 4*s will go to a retired character and not be wasted while playing the HfH store to even out very poorly balanced heroes covers.
5* - GG I believe... I think hes the only 5* that I don't have... just missed him, his release timing was pretty awful, I'd gotten my 1/1/1 OML by the time he retired into classics and I started to hoard, never been a reason to dump a lot of CP into classics since.
3* - Captain Marvel. The next two 4* CM covers from her will let me champ Carol and I like using 3* Carol to tank for 3* Cyclops, so getting her to 266 first will keep her relevant. After I max her, I'll shift to Psylocke to champ my Peggy (if you told me I would prioritize 3* Captain Marvel & Psylocke to be my first two 3* max champs 6 months ago...) This may change if I like the next 3* release, but we'll see....
4* - Cloak & Dagger, Gamora and Rocket & Groot. All of these are in the 3-6 cover range with no more than 2-3 in any color and I wanted to accelerate my progress with any/all of them. Most of my higher-covered 4*'s have at least one power at 5 covers.
5* - Hawkeye. My Hawkeye is only 1/0/1, but my highest-covered 5* is only 2/2/2, so since I'm so far away from 5* territory, Hawkeye seems as good as anyone. Seems like a fun character to play and the passive is incredibly useful.
A 5* who doesn't have 5 covers in any colour.
The 4* who's closest to a multiple of 10 in level.
The 3* who's closest to level 183, 223 or 265 (for 4* cover) or 227, 239, 257 or 266 (LT).