I strongly agree with Polkadot because it has the potential for future price increases, and also the development for Polkadot coin is already very clear that many communities strongly believe in Polkadot. But indeed for all coin that OP mentioned it has good potential. I know that Utrust coins are also quite good and can be an option, and also there are still other potential coins that op has not mentioned. Like Waves or Qtum, that's pretty good in my opinion.
I may just take you up on your recommendation about Polkadot! So far I've been investing mostly in DIVI; the DIVI wallet is launching in the UK and UE shortly, and they have just received a massive investment. The coin held value really well throughout the years except for the short Covid-related collapse in 2020. Plus, it has only just begun catching up on the ongoing bull, so it is pretty much a safe bet that it's about to go up now.