Which Line(s) to Grind Next?

Hello all. I've got 5 female crew members (+1 Santa) that will expire in the near future (Twitch Prime and Christmas), so I'm wondering what line(s) you all recommend that I grind next. I've also got the various Christmas tank discounts to use.

A bit of background of my play style: I'm fairly casual now, meaning I'll play a handful of games (<20) per week, usually to take advantage of daily doubles or any significant weekend bonuses. As a result, I expect it'll take me about a year to finish any new line from Tier ~6/7 to Tier 9/10. (As an example, I started the Maus line at the VK100.01 back in ~October 2017 and now I'm 14K experience short of eliting the Mauschen.) What this also means is I'll be spending most of my time at Tier 7/8 and probably 9, so I hope those Tiers will be enjoyable.

Finally, here's the progress I've already made, to help with suggestions:

• Germany: The entire tree is almost fully unlocked.
• USA: T71 DA and T20 bought. Is it worth continuing these lines?
• Russia: T-54 bought, KV3 unlocked, IS unlocked.
• UK: Working on the Conqueror. I'm currently on the Caernarvon.
• France: AMX1390 owned, BC25t AP unlocked.
• Czech: Nothing unlocked.
• Japan: O-Ni unlocked.
• China: T-34-1 unlocked, 110 bought.
• Poland: Nothing.
• Sweden: Ivk 103 bought.
• Italy: P.43 bis bought.

I'm considering the IS-7 because I'm already at the IS (just need to purchase it) and I have the Christmas skin for it.

Another thought would be the FV4005 line for the HESH memes, but I have no idea how the Tier 6-9's feel. Are they any good? Are they super-painful like the Churchill grind? The only issue with this line is that I've made literally no progress on it (aside from modules unlocked via the Churchills) and would be grinding (or free XPing) from the start.

Should I continue the Chinese medium line? I've heard bad things, and I had originally planned to get the Tier 9, but now I'm not so sure. That gun depression is really depressing.

Finally, are there any lines that I've already started that I should finish, such as the Italian line or US medium line.

What do you all suggest?

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