[sdiy] Which transistors for synth circuits?

[cheater cheater]

Hi all,
I was wondering how you pick out transistors (as well as diodes) for
synth circuits like filters. For example moog filter, 303 filter, etc.
Do you look for anything in specific? I'm talking about a situation
where you don't want to use the exact part in the schematic, but want
to play around with parts and see what comes out of it.

Best regards