I'd prefer Marquise Flowers to Davis or Crossen.
Personally, I thought Flowers wasn't anywhere near the player in 2018 Camp/pre-season that he appeared to be in 2017 - either on defense or special teams - for whatever reason.
In DET, Flowers has had 12 total snaps on defense this season, all of them in the Lions week-1 pummeling at the hands of the Jete. Since then, nada on defense. For the first fours games, Flowers played on 3 or 4 of the ST units, but then dropped to 2 units in week-5 v. the Packers. So, maybe my impression of a pre-season regression here wasn't exclusively related to the Pats and their schemes.
In any case, IMHO Crossen appears to me to have some Jon Jones-like potential. If the Pats are going to shed a DB, I'd rather it be Rowe. He just seems like dead weight to me now, and the cap savings derived from moving on from him would be larger (not a lot, but larger than anything saved by moving on from Crossen or Davis).
Like with Crossen, I'm not personally eager to move on from Davis or Rivers. It's essentially their rookie seasons and I'd like to see them get more time to develop, especially with Trey Flowers possibly gone in 2019.
Ultimately, of course, it's the perceptions of the coaches that matter, not ours.