Doesn’t really matter. Every def will be destroyed by heavy stacking and good boards.
Blue tanks are cool imo, since many end game players are better prepared to strike red, purple and holy tanks.
Isarnia (if tc20 only) will be tankful for that position I think.
My strategy is to use unusual teams for defense. Utility against all those pure killer teams. Just reached the magical border of 4K with mine, which kept me well above 2.4K cups since it had about 2.6K power. Ok, no vanillas, but Ares is some kind of classic.
TC20s are great to stack for revenges and attacks and also for 2 or 3 positions on def. Lianna, Magni, Joon, Sartana and Vivica will never die. Azlar is still deadly if and also Khagan and Thorne hit heavy.
All those Guin Kage Gravey Ariel Kunchen defs are more of a hype than really much better than others.
Well talented Kashs and Boldies will also tank a lot imo for keeping you in diamond. But talented legends up to +7 are there too right now. Scary