Santos ships: Javadi, Ellis, Samira, Mel (do as many as you would like)
Ah, this ask made me realize I got crumbs or nothing for my main Santos ships which you have conveniently listed, anon (save for Mel [Mentos], not my ship, I would swap for Garsantos). Virtually no Mohantos or Ellisantos/Santellis scenes (🤧) and simply not enough for Crashtos (nothing in the backend of season 2). I would rank these ships Crashtos = Ellis/Santos > Mohantos > Mentos with the first three ships being the ones I do see romantically. Crashtos has more of an edge after season 2 because they had multiple scenes together, but if you had asked me after season 1, I would have put Ellis/Santos > Mohantos > Crashtos.
From top left (blue) is Javadi/Santos (Crashtos), top right (green) is Ellis/Santos (Ellisantos), bottom left (yellow) is Mohan/Santos (Mohantos), and bottom right (red) is Mel/Santos (Mentos).
Individual ship opinions:
Crashtos: love. frenemies-to-lovers, I suppose. Definitely a ship where both are disgruntled about the fact that they like each other. I like them a lot, and their banter is their foreplay #tome.
Ellisantos: my favorite Santos ship, mostly because I think is Ellis is the right kind of mentor for Santos. 😌 I actually think Ellis and Garcia would be quite similar about compartmentalizing and having boundaries in the workplace—both seem to care about the hierarchy (see: Ellis standing up for Langdon re: being a senior resident in season 1, of course, completely void of context!) and both have their own relationship with Langdon (Ellis being in the same cohort as Langdon). So, imagining if Ellis and Santos dated, I think the Langdon issue would crop up similarly, but Garcia and Ellis are not the same people. I just think Santos would similarly be attracted to Ellis, though their relationship would look different because Ellis is, hm, gentler(?) in a way, and I think she is more of the relationship type (compared to Garcia at this stage). But Santos' issues with intimacy, vulnerability, and feeling safe would come up with any and all relationships, so I don't think Ellis and Santos would be smooth sailing from the start, either. Just different.
Mohantos: I have talked before about how I think these two are foils and similar in a lot of ways! I am so sad they did not go into this relationship in season 2, especially since Samira witnessed Langdon berating Santos. I think it's very in character for Samira to roll with Langdon returning, though (again: she lacks full context, but I struggle to buy that none of the characters have thought Langdon was diverting drugs from their workplace. Not even talking about diluting drugs, because the show itself seems to have forgotten that). Anyway, I said, "Oh there's no way this will end well" because I think they'd be just as bumpy as Garsantos, if not worse. Primarily because I think Samira would be a bad girlfriend (I love her), would not want to define being in a relationship, and that's not Santos. So, I think they could get to a good place, and I think it's clear they respect each other as physicians and Samira as one of Trinity's teachers, but it would be a trip for both of them. I want to see it though!!
Mentos: I loved their scenes together in seasons 1 and 2. I don't think Santos is mean to Mel. I don't think they're friends, either, but I don't think they dislike each other at all. I think the Langdon piece could be so fun for conflict (a term I use neutrally), but the show hasn't gone there (yet?), unfortunately. I loved their karaoke scene, and I think they could have fun together. When it comes to this dynamic, though, stans can be very defensive of either character and to be honest, I find that discourse so very boring, lol. I think they're coworkers who are a little awkward with each other, and I hope to see more of them (sans discourse).
(Ship opinion bingo asks)