Assembly shop - need a little guidance

Hello guys, I have a question and I wonder what is other players approach. I have over 20k battles, bunch of tier X already bought and others researched. Still a long way to finish tech trees for each country (ie. Polish or Sweden tanks are not even scratched, waiting for TotT discounts). I have all tanks I really wanted maybe except Centurion AX - currently grinding.

After Holiday Ops I have about 1 mln of free xp and now I wonder - should I use these resources to grind next lanes of tanks or should I get Assembly Tank? I really like to play Non meta tanks especially branded as reward tanks (like Foch155 or WZ 114). Also, I dont have single sniper tier X triangle so if DBV will be in AShop thats some good tank to fill in a gap.

What is your opinion?