Best construction toys for 4 year old?? Magnatiles or others??

[funnyfoursome]

Hi all!
I wanted to buy DS some Magnatiles for Christmas but DH thinks waste of money. He loves building so does DD age 2 and I think the 3D aspect would be great. They love duplo, less so Brio type traintrack.
Or do you have any other ideas? Thanks!

My dc adored Knex. There is a version that starts from 3 -4 yrs which i think is called kid knex.

Oh thanks! I will have a look at that!