Just to be clear...we are talking "subcompact utility" tractors right? The ones that are in between a huge/overgrown garden tractor and a true compact utility? Big enough to handle a front end loader and some 3-point implements, but not so big that you cant mow the lawn with them....something with rear tires around the 27" dia size?
As far as subcompact ute's go
I have a lot of experience with the Kubota sub-compact utility tractors....The older kubota BX2230 tractors I found really awkward to drive/sit on. It just didnt feel very ergonomic; the seating position was weird. the steering wheel was too flat and far away from you, and you constantly felt like you were going to slide forward off the seat.
That, and I didnt like how low the ROPS was. It barely clears my head. Im 6' 2" 200lbs so maybe its just designed for smaller japanese people?
and finally, the hydrostatic transmission on it was weak/not very efficient. If the wheels were bound up/stuck, I could literally 'stall' and 'slip' the hydro without actually stalling the engine....which basically says the thing kinda sucks at transmitting full engine power to the ground. Other than that its a decent little tractor
I have not driven the new BX2660 so maybe they have improved things.
We have a simplicity legacy and I love it. I find its so much more comfortable to drive compared to the kubota BX tractors. The Legacy just kinda feels more solid and its wider too, the parts on it dont feel as "chintzy" compared to the kubota. The newer small kubotas just feel kinda cheap to me compared to the older kubotas. I feel like I sit "ON" the kubota...I feel like I sit "IN" the simplicity. Simplicity is much more stable on slopes too. And on our Legacy, the ROPS sticks up a good 7" above my head, so it would be safer in a rollover...
Seat is much more comfortable, nicer/more ergonomic controls, steering wheel/seating position feels "right", and if I get stuck or bind up the wheels and keep pushing it, the hydro is efficient/powerful enough that it will actually stall the engine before "slipping". And it actually has a 'real' modern/slick instrument cluster that was designed from scratch just for the Legacy.....not just some mis-matched JC-Whitney style gauges and cheap indicator lights thrown onto the flat/cheap plastic behind the steering wheel like the Kubota BX2230. As far as hydrostatic tranny controls, I like the Legacy's side-by-side pedals better than the Kubota's front/rear foot treadle. You have to actually "move" your foot to go forward and reverse on the Kubota...on the Legacy you just have to pivot your foot on your heel side to side to go forward/back. (like driving a car/truck with an auto trans) Kubota doesnt have a tilt steering wheel, which sounds like a stupid gripe, but surprisingly does make a difference in operating comfort on a tractor.
For front end loader capacity, the Kubota BX is about the same as our Legacy. Our Legacy maybe has slightly more "curl back" strength due to the bucket curl being actuated by two hydraulic cylinders compared to the kubota that has 1 'curl' cylinder. Kubota maybe has SLIGHTLY better power steering than the Legacy. The Legacy weighs more too...
As for mowing our big lawn, nothing will cut like a simplicity's free-floating mower deck with full width rollers. You can get up to a 72" on the Legacy, I think the biggest you can get on the kubota is 60". Kubota deck is a PITA to remove and install. I can pull the deck off our tractor in 5 minutes without tools.
Biggest engine available on the Kubota is 25hp. Biggest engine on the Legacy is 27hp...and the Legacy is available with a gas OR diesel...kubota can only be had with the more expensive diesel...
Simplicity is made in USA too.
I have not driven the new subcompact utilities from John deere, NH, MF, etc so I cant comment on them.....
JMO
Ben