carl's is brian-free, jenna's has some scenes but def not as bad as other routes, and i forget about flynn but im pretty sure his is fucked-up in a different (and mostly brian-free, if i remember correctly) way. it took me at least three whole-ass years between my last full reading of 'echo' and my first time finishing 'arches' due to all the shit that brian does in this vn, so sometimes it be that way. jenna's may be the only one i can definitely say has an optimistic ending, since i just finished it again earlier tonight, and perhaps carl's does too—so maybe save them for last if you want to end your experience of the storyline on a high-note.
remember: go slow, take breaks, and turn it off if it's ever too much!