My take echoes this. If one puts any stock in streamer recommendations, Baalorlord who has at various times held spire world record winstreaks, has recently cited Monster Train as his current favorite spirelike (other than spire itself), and also cited Griftlands as a playthrough a highlight.
Baalor probably doesn’t have an opinion on Inscryption as he tends to avoid things with even a slight horror theme. I enjoyed what I played of Inscryption a lot, but very little about playing it evoked the vibe of playing spire. Monster Train is quite adjacent though, the mechanics are different enough to feel fresh but it slots into the same gameplay mood for me whereas Inscryption is just a different (and still very good) thing.
Neither has the tight balance of Spire or feels quite as deep strategically to me (though in all honesty I’m probably not a strong enough player to be trusted in this regard), but both are fun.