Maybe I'm just old and lazy. When I was a kid I used to build massive Mechano sets with my dad, using his stuff from when he was a kid. I'm not really into maths or engineering so maybe that's why I don't care for it any more.I like Technics as, once you have a few sets, you can scratch build some amazing stuff.
I have a remote control Lego Creator TRex that walks, which is one of the best sets I've built.
https://brickset.com/sets/4958-1/Monster-Dino
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Should really take it all out and introduce my kids to it. My eldest is 6 and still struggles with the pins a little so Technic & Mechano maybe in the summer..