The F094/s is the best when turning left and right is concerned. The only difference the F686/m makes is on horsepower tracks "Test Course, and SuperSpeedway"
The F094/h is an ok chasis, its major flaw is that it has more understeer than the F094/s.
The F094/s has 829 HP, and the F686/m has 972 HP.
In a direct comparison at Midfield I gave an all out run in both the F094/s and F686/m. Pushing the limit while keeping everything legal for Times Database submissions I managed a 48.703 in a F094/s. Just the same in the F686/m I managed to get a 49.144. Midfield is more of a horsepower track since even with a lesser chasis you can gain time in the straight aways over a better handeling yet slower in the speed's car.
At monaco "cote d azur" i've done the same as well. In a F094/s i've done a 1'06.894"with room for improvement" wall touch free run and in a F686/m i've done clean low 1'08's with a slim possiblity of cleanly getting into the high 1'07's with a bit of luck.
Monaco is a handeling track, with its short "straights" you really dont have the ability to make up time on the straights. This type of track is where the F094/s really shines since it handels much better than all of the F1's in GT3. Its still the best F1 in GT3 when your on a road course, it just really shows it even more at Monaco.