Kubota makes good quality equipment. My only issue with them is that they can be very light weight in construction vs some of the competition. Just not beefy enough for my taste. For light work they are fine but using heavy implements can be a problem long term for them.
When you get to the M series kubotas......They are every bit as heavy duty as the competition. And 65-80HP puts you into that category.
For what you describe your needs are, all the major brands as mentioned, including kubota are worth a look. And they all spec similarly. Sure, some are bigger and heavier, but some are smaller and lighter in that HP range.
But you asked was what was a good, comfortable, and reliable tractor in the 65-80 PTO HP range....to be used for mowing, pulling a disc, loader work, etc.
Perhaps if you had asked what is the heaviest, biggest, beefiest tractor in that HP range, you would be getting different answers? So what exactaly are you looking for.
And perhaps it would help if you knew (or could share) what implements you plan on running. How big is the disc? Bushhog? How much FEL do you need to lift? Plan on lifting 2-ton pallets of whatever? or just a loader tractor to push dirt / brush around.
OR perhaps look at the new kubota M5 and M6 series. The
M6-111 at 82 PTO HP and 9600# weight....they dont get much beefier at/around 80 PTO HP.
The think about tractors......unless you are shopping for the biggest of the biggest, or the smallest of the smallest......no matter what you end up with, there is always gonna be something bigger/beefier.