Inscryption is not close to StS in gameplay style. It's more narrative and the card gaming strategy takes a back seat, it's also very breakable with certain strategies. Not to say it is a bad game, just it doesn't sound like it's what you're looking for.

Monster Train is a solid game, you'll get more replayability if you get the DLC later since it impacts core gameplay.

I would actually recommend you check out Griftlands, it feels closer to StS playstyle to me than Monster Train. In Monster Train it's a lot about supporting the units with your deck, whereas StS and Griftlands are more about using your deck for the combat.

I hope you're not disappointed by Inscryption, because it's not going to be what you expect. But it is great. Don't look anything up before you play it.

Inscryption > monster train by a wide margin. Go into it as blind as possible. Don’t look anything up. It’s the most memorable deck builder that I’ve ever played. I wish I could erase the game from my mind so that I could experience all over again.

Monster train was fun but I felt like there were runs that were pretty much unwinnable from the start due to RNG. Unlike Slay the Spire, some of the classes just didn’t feel viable. I only played it with the DLC enabled so I’m not entirely certain how the base game felt.

TL;DR there’s absolutely no situation where I would ever pick Monster Train over Inscryption

I’ve never played monster train, but inscription has a little more going on than just a roguelite. I don’t want to spoil anything, but depending on if that sounds interesting to you, that may be the answer to your question.

Monster train is very good. It's probably a bit easier than others in the genre. It's more about how many modifiers you use to make the game more difficult than simply finishing. You can generally always beat the game on any given run, you aren't as dependent on getting the exact right cards or unlocking more powerful cards.

I can't speak too much to the dlc, I don't have a ton of experience with it, but my friend has literally unlocked and completed everything and still enjoys the game.