The only real great GP for Casey has been Portugal, and it is already too far in the past. He needs to do something or they (Honda) will be quietly steamrolled like in 2010 (by Lorenzo/Yamaha). You don't only have to be fast in a bike, you have to use alternative views/riding when the bike is not that perfect. Stoner is still in a reasonable course for a title, but he has not much time remaining. I go on wonder about his arm...
Pedrosa is still not out of the picture... at least to beat CS in Honda.
Rossi is lame in dry conditions. His Silverstone's lap times are pretty horrible. He is not being able to cope with not being a top contender. I am sorry for Ducati, as surprising as that phrase can sound.
Espargaro is a real threat to Marquez, who is passing a relative low period. Espargaro was a fierce rival in 125cc, with not much speed between them. They are completely different, Pol being much more aggresive. I don't see Luthi easily overcoming those two with just his regularity.
Vinales is the force in Moto3 and Cortese is the typical steady rival. The thing is Vinales, although very young and still unexperienced, has a cold head, so he is my favorite for the title, which is hardly surprising.
And finally, about sidecar racing I am not going to give an opinion, mostly because it doesn't exist anymore in FIM GPs