For many years I've owned an H316 which has been my only Series 16 machine. I'm not really sure that one machine constitutes a "collection". However, in 2006 I bought a DDP-516 machine that I've been restoring.
In addition to the two machines I have some peripherals. These include both an optical and an electrostatic paper-tape reader, a paper-tape punch and a pen-plotter.
I do not own a teletype, which would have been the usual input-output device for machines of this vintage. I've mostly used a PC as a terminal instead. This has the advantage that the PC can also emulate the action of the ASR's paper-tape reader and punch, and so operation is possible without using paper-tape at all. I've recently started using a FACIT daisy-wheel electronic typewriter that has a serial interface as a KSR (Keyboard Send Receive) device. I've had a long association with this machine since it was used, when new, as a printer connected to various CP/M machines running Wordstar (a word processor package). I remember many frustrating hours getting the proportional spacing to work properly.