DEC terminals for New England Digital Synclavier II

Hello, I'm looking for a bit of information regarding old terminals. My New England Digital Synclavier II (an old computer based music synthesizer) has the option of having a terminal connected via RS232, and the manual specifically mentions the following three terminals: VT100 VT640 ADM-3A Am I correct in understanding the first two are by DEC (Digital Equipment Corporation) and the third one is by Lear Siegler? How common were and are these three terminals? I'd like to get hold of one for use with the Synclavier, just wondering what views people hold on them, both from a popularity point of view and in terms of usability. Presumably you get a slightly different experience using all three, at least in terms of build quality, display type, keyboard type etc, if not in terms of supported terminal modes as well. Curious to hear what people think. If you're interested, there's a video of me demonstrating the Synclavier on YouTube. http://www.youtube.com/watch?v=ZuUh4eIE3-k Richard