Personally, I’d do Kingston, as you have no maxed 5* green snipers, and he’ll pair nicely with your Evelyn.
Telluria makes an amazing tank, and a great support hero, but you already have both of those covered just fine - and Telly can still be a solid support hero at 70 (sturdier stats for it)
Heimdall is amazing, as he’s the only hero to add temporary HP, but you’ve already got MN as a healer in green, so think he can wait too. & Again, being 100% support, he doesn’t benefit [as much], as a sniper would, going to 80. Can still use all of his skills the same at 70.
After that though, tough call. I’d do Heimdall for offensive purposes, or Telluria for defensive purposes - so really depends on your priorities [then].
As for red, not loving any of those options, but if you can max three, you may as well go ahead with at least one [while you wait to see if you land GM next month]. I’d probably choose between Mitsuko, Grazul and Natalya personally. Mitsuko is very niche, but super fun to use and the best counter to any blue heroes, Grazul has some amazing offensive protection capabilities that’ll be of great use almost always considering where the metas heading, and Natalya’s fast mana control is amazing (and completely underrated; she’s one of my favorite reds I own).