Free Tier VI, Don’t Know What to Pick

So I ended up with the "Back in Action" missions after a long hiatus, and ground through the boosts to FR heavies and the Yoh heavies. Now I get to pick a free tech tree tier 6 and line of discounts and have no clue what to go for. My main thoughts so far were

(1) KV-1S to go towards obj 277, though I already have blueprint discounts for some of those tanks.

(2)Jg.Pz.IV cause tring to get through the other german td line is giving me way too much stress, I hate fragile tanks.

(3)WZ-131G cause I hear CN TDs are pretty good.

(4)Bassotto for mom's spaghetti

(5)Type 58 to go up a CN heavy line (which one though??)

Any advice is welcome. For reference, I'm already well up the swede heavies, all US heavies, Brit heavies, US meds, ITA meds, FR and UK arty