So far I got an EST Integrity, Wheelock MT-24 LSM, a BG-12, and a 4251-21. I am getting ready to buy the next batch of alarms (Pull and horn/strobe). I don’t really one ones with wire nuts just yet, but here is a considered list.
Just get whatever you really want. Just make sure it’s the right voltage and its coming from a good seller. Most importantly find a good price and don’t get ripped off. ~$20 is fair price for most used devices.
Personally, if you’re just looking for an alarm to mess around with, I would recommend anything newer Wheelock (AS, NS, MT, RSS, CH-70, etc.), though I also like classic Spectras. For a pull station, I don’t currently own any of the pull stations on your list, so I couldn’t really say, but the JBG-10 sounds like a nice choice.
Keep in mind that the SIGA-278 is addressable. The conventional version is the 278B-1120. As for the ESL pull, its also sold as the ADT 5050-001. In terms of signals, if you dig enough you might be able to find Spectralerts for dirt cheap.
I would personally stay from a BG-10 as a second device. Reason is a BG-10 (and not BG-10L) uses an allen screw to reset and it takes a while. Plus they are easy to damage and pull by mistake. Also, I would stray away from FCI MS-2 pull stations because in my experience they don’t last very well if they’re pulled a lot.