Mint so far has avoided forcing snaps, I will jump ship too if they do.

What about LMDE?

That's barely even a real distribution; it's an escape plan for Mint to leave Ubuntu if necessary. This is not a serious suggestion.

OP mentioned stability and long-term supported as what he’s looking for. The Linux Mint team have stated LMDE is more for themselves to gather info and not a priority. So I would stay away if looking for stability and long-term support.

“We work on LMDE primarily for us, to get that information. It is not a priority, certainly not compared to Linux Mint itself…” https://blog.linuxmint.com/?p=4276