On guesswork so far, id have it as this:
_0.0 Scuderia Ferrari
+0.3 Red Bull-Honda
+0.5 Mercedes AMG
+0.6 Alfa Romeo-Ferrari
+0.7 Renault Sport F1
+0.8 McLaren-Renault
+1.0 Scuderia Toro Rosso-Honda
+1.3 Haas-Ferrari
+1.5 Racing Point-Mercedes
+2.5 Williams-Mercedes
I fear for Williams as this season will be long, seen encouragement from Mclaren who will fight their customer partner Renault. Ferrari have a car thats just that great out the box, that will improve, Mercedes are behind so i feel. Both Honda powered teams will improve, but the Honda will still be a weak point. Haas and Racing Point are solid cars, one unreliable and one lacking performance a little. Alfa Romeo will be the surprise as Ferrari will use them to try and disrupt Mercedes and Red Bull early in the season.