I've got all of them from the 407 on. Prior to the 407 was a bit before my time in the industry, but I've helped a few people out with basic measurement stuff on a few of the older machines. We've got Bristol stuff from the Amocams on up too... Recently, I find myself gravitating towards Control Microsystems because it's a little easier and a bit more cost effective to implement control logic since they allow ladder and C without having to get too crazy on purchasing software. Pair a ScadaPak with a Red Lion G series HMI using modbus, and you've got some serious horsepower to play with.
The ROC's are just so much easier to add any data point on the machine to the history archives. FST's are nice, but they can become cumbersome very quickly.
Edit: Rosemount wireless sensors are very very cool with the x-bee meshing they do. Implementation in a ROC800 is simple too. Pop in the card, pair up the devices, do what you want with the TLP's. This is one area where Emerson still shines pretty bright in my eyes. Accutech can do it, and their stuff is packaged nicely but they can't mesh the wireless devices so all the remote sensors have to have a path to a master radio. Wireless pneumatic valve control is the way to go!