I'd consider getting a Eurorack modular synth.
Advantages:
1 - it's much more fun to build your own synth out of components than to buy an off-the-shelf system designed and built by someone else
2 - and you get to build exactly what you want
3 - there are literally thousands of modules to choose from, giving you much more flexibility and features than any integrated synth
4 - lots of cables to make a patch, which can be fun to mess with and interesting/intriguing for audiences to look at
5 - audio and control voltages are the same, so you can do things like change synth parameters with audio
Disadvantages:
1 - price, typically much more expensive to get equivalent functionality to a cheap integrated synth. [A]
2 - size - much bigger than a typical integrated synth [B]
3 - lots of cables to make a patch, which can make recreating a patch a pain compared to a digital/hybrid synth
4 - can look intimidating to someone unfamiliar with modular synths [C]
5 - making a modular patch can be slower than just dialing in a digital patch
Notes:
[A] - But you don't necessarily need to replicate everything, you can have partial functionality that will still be useful and fun, and may get effects that would be hard to get any other way
[B] - though Eurorack is still much smaller than some other modular formats
[C] - But it's not hard to pick up, and learning modular synthesis is fun