Cellpose[0] and Stardist[1] are the two you'll see most heavily run and talked about on the forums[2]. They're classic CNN's, but it just feels like they (and any modern models) are swept up in "Go out and buy a 4090.But these guys will give you plenty of mileage before you have to reach for the bigger ones.

[0] https://github.com/mouseland/cellpose

[1] https://github.com/stardist/stardist

[2] https://forum.image.sc/