So let's sort through some of the FA SP options. I took every pitcher from this past season who threw at least 100 innings, and set up 4 flags:
IP - Did they throw at least 150 Innings? A major reason we need a SP this winter is lack of durability from the young pitchers currently in org
ERA - Did they manage an ERA under 3.80? League-wide starters had a 4.09 ERA, so 3.80 is a cutoff for results that you'd consider an unequivocally "good" season
xStats - Did they manage an xFIP and xERA under 3.80? Between these two numbers, xERA taking contact quality into account, xFIP purely distilling to peripherals, you can largely triangulate skill and avoid a luck based ERA mirage
Stuff - Stuff+ and PitchingBot are both available on Fangraphs and have very different approaches to quantifying stuff. I flagged every starting pitcher that at least one of the two flagged as having above average stuff
From there, how many guys met each threshold? Below are the FAs that met all 4, 3 of 4, and 2 of 4.
4's - Corbin Burnes and Max Fried
3's - Blake Snell (missed on innings), Yusei Kikuchi (ERA), Jack Flaherty (stuff)
2's - Nate Eovaldi, Nick Pivetta, Luis Severino Michael Wacha. Sean Manaea, Andrew Heaney, Jose Quintana
I feel like this largely tracks with perception. Burnes and Fried are stars, the next three guys have a wart or two that keep them a tick behind (they compare to Steele and Shota who came in as 3's for instance), and the 2's are all guys who you probably like but almost certainly don't love. I will note, since he's my guy, that Nate Eovaldi *just* missed being a 3 because his ERA and xERA were between 3.8 and 3.9. I'd consider him like a 2.5.
And then I don't want to go through every possible trade option, but some regularly mentioned ones:
4's - Framber Valdez, Kirby and Gilbert from SEA
3's - Crochet (innings), the rest of the Seattle guys
2's - Mackenzie Gore, Brady Singer, Reese Olson