CROWS! Besides the fact the writing is miles, decades, a fucking million leagues above and beyond the Watchmaker (Watchmaker author is 21, SoC author is 43. One writes like someone who has something to say/has lived life, the other writes like a YA author who's cashing in on the Oh gay boys are cool now in lit). But, yeah, besides that, the SoC is just meatier in it's plot and characters and heck, even thought out of cast of 6 (or ten) two of the main characters are the gay cute couple and there small bits of interaction is way better than the whole book of Watchmaker's MC who is in love with another guy through out the whole book.
Crow also has a squeal, which is a must read. So I would recommend read both! But read Watchmaker first becasue it's light and easy and kinda boring at parts. Then when you get it out of your system jump on Crows and you can come back here and thank me later.
You also can't compare them cause they have very different plots and tones. But of course I would pick Crows out of the two.
SoC rating : 11/10
Watchmaker : 7ish-8ish/10