Knex is great! I had a small set growing up, but never one of the big dynamic ones. Did you ever come across Capsela? Another fun modular building kit. The floaty set was awesome.
Capsela was really cool! In the end I feel like Lego with the Technics and Mindstorms stuff caught up but for a while Capsela was some of the coolest stuff you could get for making mechanical/electrical systems.