Ok neat, we’ve played all three of those.
Agree with Craig that Oz is easily the best of those, followed by Noside. Tombstone Express was decent but there’s a really gimmicky dexterity bit that annoyed me. It just seemed like a weird addition as a time suck. We just ignored it since it had zero impact on the actual game other than stealing time.
If you have time to do all three, would do them in the Noside, Tombstone, then Oz order. I think it’d be best to have at least one other Unlock under your belt before taking Oz on.
We haven’t played Last Tale but I also agree with Craig on the others he listed. We’ve also done The Island of Dr Goorse, which had a really neat final puzzle for us, though a good chunk of the early part of the game has you split up your group. My wife & I usually do the Unlock & Exit games on our own as we feel they work better in a really small group.