Based on the last contests I guess Italy, San Remo does bring quality.
Russia is another likely option. They have a big music industry, we know they can take the ESC seriously, and they get quite a few extra points from their neighbours.
France has stepped it up and unlike some years ago they are now among the more promising countries.
Bulgaria: Taking the contests seriously for years in a row now! Keep it up!
On the other end of my probability-of-winning list:
Spain: Unfortunately TVE seems to be absolutely clueless about the ESC.
Portugal: Judging from the FdC 2018 edition, the year after they won, Portugal has a looooing way before they will be getting close to a second win.
Switzerland: I'm already dreading this.... probably another disaster. I will let history speak for itself.
Actually it felt kind of easier prediction who will most certainly NOT win.... and I could go on...