<p>I went through a similar decision making process. You need to be clear about what your photographic needs are. If you need reach, then a D7200 is the only real choice. The body will be the cheapest possible upgrade to your D300 and you will have money left over to buy accessories. Don't fret too much about the SD cards, memory is getting cheaper and faster every day...I use a 32GB card which cost the same as the 4GB card I used to use in my D300. </p>
<p>Don't worry too much about the consumer body type, you will adapt to the controls. There will be times when you miss the D300 controls but difference in image quality will more than make up for it, IMO. I found that adding a battery pack made a world of a difference in handling. </p>
<p>If you are inclined towards FX, then logically the D750 is your best choice but will be costly not just for the body but for also new lenses. I wouldn't go for a D800e unless you really need the extra mpx. </p>
<p>All of these three cameras have considerably greater resolution that the D300 and require a bit more care with regard to handling. </p>