[wiredfool]

Sort of kit based, but there aren't that many lego pieces that only work for one type of thing, everything can be repurposed if they have enough other bits and pieces. (though frankly, right now all thelegos in my house are in dump truck form)

Konects are kinda cool, but the variety of what's straightforward to make is lower than Lego.

Plain old blocks are the other big construction thing around here, supplemented with some rough cut rounds from our forest. Overall though, I'd say that the legos are used at least as much as all the other construction stuff combined. Ymmv, I've got three boys, 6,3.5 and 1.