Just to chime in on the lower end of the spectrum in 4*land. There are a number of variations to go with the required PVP toon.

Grocket/Polaris
Polaris/Sabretooth (the counter to the above)
Knull/Polaris
BRB/Polaris
Medusa mixed in with all of them.

Probably the most skipped team from me is the Knull team because he adds too many free moves.

On another note. I have almost all of my feeder 4*s at 10 saved covers, which means I will have the ability to roster all 5*s. That was my "sign" that I would start champing my 4*s, just my most used 4*s.

On the loaner bit, I was not speaking of the actual loaner. I was figuring that was nbperp’s choice of terms for the featured character. I use the actual loaner only in my first few matches where they are the dummy teams and I wipe them in one hit with Thanos.

My Hulk is at 5/3/5. If I'm going to swing with Red, I want it to end the match before the self-damage aspect hits Hulk back, or just do so much damage that it's worth it. OK's red is very situational and likely a non-factor in these matches.

I want Ok in front because I want her to preserve as much TU AP as possible all the time. Maybe she heals, maybe not and I use a healthpack, but I need her facilitating the KOs and Hulk is weaker for every TU you give away with him in front.

Tangentially, it's wild to see the seconds count down on events now. Glad they added that.

One more thing. Cosmic Chaos is quite a challenge in SCL 10.. Yowza!

Just as a reference, over the past five days my rate has been up.
Current pulls: 216 (+21)
LLs: 91 (+13)
CP: 3140 (+205)
That is a rate just over 4 pull per day.
The last span was just over 3.

Regardless, I use 3 per day as my rough estimate for stuff. That way I know I am on the low side rather than being overly optimistic.

Since 12/14/20...
LLs: 23->91=+68
CP: 1056->3140=+2084
Pulls: 65->216=+151
Over 44 days, that is 3.43 pulls per day.

At that rate, by March 8th (40 days) I am looking at +137 pulls, or a total of 353.
I will most likely dip into that to try and roster Yellowjacket, of course, but that is one fewer cover needed on March 8th.

There is another PVP after She-hulk. I think this will be the first time I can make a full 10,000 point progression in PVP since I started SCL 10.

Nice...too bad it is for Red Guardian.
Oh well, at least he is a feeder.

I am hoping Throg is next, but it might be Scorpion.

Any thoughts on who I should take on as my next 4* favorite?
I currently have Polaris tapped. She is currently just a couple of shards away from 355. I am thinking I will keep her on until 360.
I am leaning towards 4* Thanos right now. He is currently at 303. His green is dealing 1939 per special tile destroyed.
Among my frequently used 4*s he is the lowest level.
My general usage is...
PVP: Okoye, Immortal Hulk, and the featured toon.
PVE:
3 easy nodes: Gamora, Grocket, Juggs
3 hard nodes: Kitty, Grocket, Polaris OR Okoye, America Chavez, and Gladiathor
3 essential nodes: okoye, Immortal Hulk, and the essential
Challenge node: BRB, Polaris, 4* Thanos

The way I see it is that I want to stick with someone I use rather than someone I don't. That pretty much narrows it down to Chavez and Thanos. (The other 4*s listed are all maxed or 360+ already.)

Chavez could benefit from a little more health, but really her job on that team is to generate crit tiles. Her level is not so important.
But with Thanos, well, he is used in the challenge mode, and it is his green power that fuels the whole team, so making that a little beefier should theoretically speed up my performance in the challenge mode.

Any thoughts?

Karnak is another I would consider, btw. He is really good. I just don't see him filling any role in such a way that i would be picking him over the stuff listed above.

I would target 4*Thanos, because you actually use him and the better he is, the faster that challenge node will go

I Support 4* Thanos for utility. When he gets smacked out by a bad board or whathaveyou, it slows things down and the more health he can have, the easier time you can have.

Thanos works well. With what you are proposing. I think I should look into using that team. I have been using Apoc/BRB/Polaris for the challenge node, but it is slow unless I can consistently get black for Apoc. BRB and Thanos can pretty much infinite unless the destruction of the tiles does not trigger Polaris.

Does Thanos's Green trigger Polaris?

It does indeed.

The weird quirk I have noticed is that it does not seem to trigger her if his green hits a fortified tile.
I call that a quirk because matching a fortified tile or even destroying it with a match-4 blast does trigger her.

By the way, one big help I have with the Thanos/BRB/Polaris team is that I have 3* Atlantis on Thanos and 3* Yaro Root on Polaris.

1 more. Are we supposed to be getting a new 5 in LLs soon?