“Best” five vehicle Soviet lineup for 4.0-5.7?

I’m not planning on progressing any higher than 5.7 just yet, so I’m thinking of hanging around in Tier III for a while.

Currently, I have the T-34 (1942), KV-1S, T-50, SU-57B, and BTR-152A for my lineup. I like the idea of having one of each class, but am open to suggestions as to why I shouldn’t. Adding a sixth or even seventh crew, and getting Premium vehicles are not in the cards for financial reasons