Almost impossible question. I agree with the others that said first you have to figure out what you need, then start shopping color and or price, what ever is your primary concern. The view people have of the local dealers and local feelings about the brands drive the used prices.
I also found in this area there was not too much savings on buying used from a dealer. I heard of but didn't actually see any real "deals" from private parties. The only way we could have gone for less than we did was to go very old or gray market. The used tractors we did see seemed to be pretty well beat up and not all that much savings. We also shyed away from certain other brands due to either distance from a dealer and or the dealer, like out of his back yard. Don't get me wrong, they may be great tractors but just not sure how much support I might get from a garage in a back yard or having to go three hundred miles to get parts.
I might have gone Deere, wasn't all that much more by the time we got what we thought we needed but the Orange dealers seemed to offer more support at less cost than did the Deere dealers. One example of that was all the Kubota dealers telling us that they will pick up and return the tractor for free for any warranty work. Deere just laughed at that.
We buy few year old cars and trucks too so were a bit suprised that we could not save any doing it that way with tractors.
If indeed price or "value" is primary to you, figure out what you need, then look for the best deal of any color tractor that will fit those needs. We started thinking about Chinese then grey and then we went looking starting with Case, then Massey, then NH, then Deere and at last Kubota. We bought Kubota but if the Deere salesman had been in one time when we stopped we might well have gone green. The
L3830 will do what we need but a Deere 4410 would have done it as well and I really wanted a 4X20 from Deere. We also were very close to getting a MF 1433 and it would have been okay and the best "deal". However in hindsight we would not have got the equipment we later thought we needed (foamed tires and combination bucket). So, take your time and think about what you need and what you want versus need and your local conditions, your land, the local dealers and what you see around you doing work.