They're all good Chris, and it's not easy to choose from any of them. My favourites are the ones with the blue in them, obviously the plane stands out more and blue skies make everything look nice don't they. I would perhaps have cropped in No.2 as the large white cloud lower left is quite distracting, or tone it down a touch.
My ramblings about the others, in order, below.
1.Really cool but I'd have put more in front or behind it so it wasn't centre centre, nice to see the jet trail though.
3.Great shot to get the burners in, lovely colours that punctuate the otherwise grey scene, and nice to have the lights in it too, shame the plane isn't a touch bigger, it would probably look much better at a good size in a frame on someone's wall !
4.Great shot, again nice to see the jets glowing like that, especially the cloud getting darker toward the outside of the shot. Again better at full size.
5.Fantastic heat haze, I really think with so much of the underside well shown you should have zoomed in on this some more, how big are the images, I bet just the heat haze and the after burners going out of shot would make an effective and interesting crop.
6.I know it's good to show the sky but I feel it's too much in this one.
All great shots though, where you on the ground ? How many did you take that you didn't post