I have ‘let go’ of all of mine: even if they reappear you are saving only a little time, assuming they work the same way, each being a partial set/stack which you didn’t have time to complete.
At a guess? The love letters which tie into seasonal Valentine events could re-appear in Feb so seem most valuable. The heart similarly, though I can’t remember how that fits in. The orb and coloured thing seem less likely they’re not as well established –I think each was only used once. The coins similarly.
Antimony gear hasn’t resurfaced so should re-appear in some form; probably not as a dedicated season, but they could use unlockers in the same way. Might be worth waiting to see what they do with them.
The rest seem highly unlikely. The Construction and Alien events were quite a slog, and I can’t see them repeating those in that way. Both types of items have re-appeared since without needing tokens. The Oryx token is very old – an old MotMG I think. MotMG now is more an excuse for releasing whatever new content they have, and each is different. I can’t imagine them revisiting one from years back.