A Synthi AKS (VCS-3 in a case) was my second synth (bought from David Pritchard - "Noctural Earthworm Stew" - if that means anything to you). I really appreciated all the basic synth power in a small briefcase and I felt like a secret agent (with a case full of gadgetry) when taking it home on the bus from Toronto to Ottawa the first time. I think that nowdays you could cook up a similar small, shallow Eurorack system in a briefcase (though without the speakers).
It's one of the synths I regret selling years later because it is so self-contained. Besides the basic 3 VCOs, Noise, VCF, Envelope and VCAs, it also had a great ring modulator, spring reverb and powered stereo speakers plus the wacky keyboard/sequencer. If I still owned it, it would hang on a hook in my kitchen wall like art and I'd twiddle up strange sounds while waiting for water to boil and for listening while washing dishes. Could just grab it from the hook to take to a jam.
Its self-contained nature was also the reason I sold it. Everything was non-standard. The control voltages were not 1V/octave. The Trapezoid had a linear output instead of exponential (which I prefer most of the time). The sequencer could not be synced with other instruments. I really wished for octave switches on the VCOs when I was using with my rock band. I usually just set up one patch per set during breaks and my Minimoog did the heavy lifting, as it was fast to tweak. You can wire up pins to 1/4" jacks to interface with other gear but you have to be careful about scaling, polarities and such. (The built in meter was a huge help though, for understanding what's going on. I eventually built a meter into a Moog cabinet but it didn't have the nice zero volts at 12 o'clock response to observe voltages moving through both polarities.) When I needed money to buy my first proper half-track, it was the logical instrument to go because I couldn't get it to play along with my other voltage controlled synths without convoluted patches involving the patch bay in my Korg 3100 (which had some handy modules available).
I've recently bought a VCS-3 app for my iPad which sounds very good and adds more capabilities to the original but in a confusing fashion. I believe it will reward more time spent learning its new elements and configurations.