It is never a bad idea to buy the most power/ most features you can afford.
I agree.
You didn't say if you're looking for new or used, cab or open station.
I've just been through the tractor shopping process and decided on the JD 5085M. This will be the first JD in several years. As you can see in my signature, the other tractors are blue. The new JD has a cab, my only tractor with one. I bought a cab tractor specifically for the hay field. (I have a JD 457) The 5M series is the "premium" in the 5000 size. It has some features that are really nice and not available on the others. I thought the price was decent, for what you're getting on the 5M.
BTW, I've checked prices on used tractors. A few days ago, I went to a huge tractor auction (Idabel, OK) and watched a 5075M Cab, MFWD, FEL with 300 hours on it sell. I just bought a brand new 5085M for $10,000 more. My tractor has everything that the used one had, plus 10 more horses, radial tires, electric hitch, and power reverser transmission.
on edit:
I forgot to add that JD has 0% for 48 months financing on the new tractors. Another reason that I bought new instead of used.