Come on, you are not locked into just 2 doctrines as Soviets, don't bullshit me, and don't even try to say soviets have only 2 viable doctrines.
That depends if you want to actually win or just play.
If you go for wins, you're forced for shock frontline or ISU as static play with guards therefore guard rifle doc is heavily punished in current meta by indirect weapons and flames.
Sure, you can go hipster and play other doctrines, but only recently soviets can use more then two doctrines on meta level.