I don't see the fenders as an issue. I think they might be fiberglass or impregnated plastic. They don't rust, they keep the mud off, and they are sturdy enough for someone to sit on while riding 'shot-gun', though not particularly comfortable which is probably a good thing- keeps people from doing it much.
I've never owned or operated a Kubota, but this NH has been flawless. Once had a problem where it wouldn't start. Turned out the sensor that determines if someone is seated on the tractor (a requirement for starting) had seperated at some connector where the wires ran below the platform. Pretty quickly figure it has something to do with the seat and found the culprit. Reconnected it. That's been the only problem in about 1000hrs of use. It's my father's all purpose farm tractor but it doesn't get a ton of use. Those 1000 hours took about 4 years to put on it. It's used for cleaning out the barn, running a 9' cutter machine, raking hay, it can and has run a square baler with kicker, hay rake, 5' HD brush-hog, log-splitter, 5' box blade, hauling firewood, etc. When the 90HP Case was down we used it for a few days to run the 4x4 round baler. It actually did okay with that but the rolling nature of the field made that unsafe. It got pushed around.
My guess is the Kubota has better FEL capacity. I don't actually know what the 16LA should lift but I know it could not unload 3000# pallets of lime plaster from the rear of a tractor trailer. It has no problem lifting 4x4 silage bales however.
I'm sure they are both solid machines (or could be). I think overall condition, add-ons like filed tires, rear-remotes (a $1200 add-on we did several years ago), and overall preference would be the deciding factors.