I kinda like the middle one the best, you really need to have blue-black-white in that order somewhere on the flag, to still represent the classic winter imagery of blue sky, black forests and white snowy fields.
The bottom one also contains that combination but is too similar to the Finnish flag.
Seen in Hocking Hills Ohio (sh.itjust.works)
This was very cool to see, if you know what it is please let me know.
It's no secret that Estonia has a desire to be a Nordic country. Using a Nordic cross flag has been discussed many times throughout history. There's a few options, which do you think looks best? (files.catbox.moe)
I probably vote on the top alternative