Almost all attachments are standardized now, so everything fits everything. If you have multiple hydraulic circuits on an attachment, then it becomes proprietary.
I have put many different (one hydraulic circuit) attachments on my bobcat. I have loaned my attachments to guys with Case skid steers: no problem. We even had a contract that stipulated that we use a Caterpillar machine, so we put our attachments on their machine. Their machine couldn't run the Bobcat hydraulic angle broom, though, so we got to use our machine anyway.
I have my John Deere tractor retro-fitted with a universal mounting plate, so my tractor will run all our universal attachments too. John Deere is fond of putting their own proprietary attachments on their tractors, but all their skid steers are universal mount too. The same seems to be true of Ford/New Holland tractors and skid steers.
Bobcat has great attachments, well integrated with their electronic controls in the cab. Hook up a multi-circuit attachment that isn't Bobcat...it ain't gonna work. Even my Bobcat dealer can't make their computer run a different brand. The only solution is to buy the brain from one of their attachments and wire it into yours. Keep in mind that this is only true for the machines that do two or more different hydraulic function on one hydraulic service circuit.
I imagine that New Holland skid steers are very universal. Since they don't own a major part of the market, they will be stuck with following the leaders.
Regarding controls and New Holland: I can't comment, as I don't run them. All the manufacturers seem to be going to a universal hand only control style that doesn't use the feet except for throttles. I don't think you can even buy a bobcat anymore that has the old style foot controls. If you can, I am sure it is an option.
The Case operator control system seems to be the same as Caterpillar. I suspect newer New Holland is the same, too. My bobcat is different (and much easier!) but it is switchable to the other style if you prefer (I think). It is "drive by wire".