I moved up with the need for ANY loader, more HP for bigger brush hog. SO I sorta looked at those things more as buying 'points'.
I went from kubota to kioti - more features for less money. And their deal was free loaded tires. EVERYONE here loads their tires, last tractor did not have them this one does. This one is double the weight (3300lbs est compared to 1500) and it's MUCH more stable on unlevel ground.
The QA is std - wouldn't have gotten a tractor without it, as one task is moving roundbales and clamp on forks move your pivot point even farther out. I got the cheap ones from titan (palletforks.com) and they're great. For 90% of what I've done it's been a non-issue, light rear wise. I did move a large bundle of rough cut lumber and found the loader can out lift what the rear can handle...had to use 4x4 to even move the tractor as the rear was too light. But I've moved very large rocks and logs and not had a light rear end. Convenient to NOT have to go get a ballast box or other implement for weight.
HP..I went with 35 over 26 - only $1800 more. 40 is their biggest model in that 'frame' size but was $2500 more yet..not worth it. One can always use more HP! If not..it's not like it's in the way or anything. I have managed to stall it a couple of times (HST) going into brush piles to push them about. No matter your HP you can still 'overload' it I suppose.
I opted for rear remotes, rubber floor mat, cruise control (hst and brush hogging it's a godsend), link pedal, mirror (love it), arm rests, the filled tires of course. Plan to add a hyd top link soon I think as i do a lot of box blade work and just got a disc harrow and adjusting the angle of attack changes what these tools can do and doing it from the seat would be handy.
More weight does have a side effect or two - you'll need a trailer that can handle it should you need to move it about, and you'll likely see ground impressions. The kubota left no real marks on the ground..this one is leaving noticeable impressions outside the barn door on the grass from the in/out all in one place nearly daily.
BTW, I paid 22450 out the door. The options listed above - totaled $640. Yes, two rear remotes were added and only cost $295.
The CK3510 over the 26 also gets a heavier loader as part of the upgrade. 1800lb lift capacity.