Hello IAMUser,
First, know that MIM is mostly a rebranding of FIM: MIM is FIM :)
The end of life for FIM is definitely prior to 2026, so if you want to have the extended support till 2026, you should migrate to MIM.
I don't think you will find many articles that compare FIM and MIM, but you can look at this one: mim-fim-ilm-compared
Kind Regards,
Sylvain