There are other brands that are just fine, but you will occasionally get missing pieces, poor fitment, poor/strange construction etc... With LEGO you'll not get any of those (except the occasional strange construction).
I used to buy ~50/50 LEGO/Clone, and despite improvements in clones, it's 95/5 now. The LEGO experience is simply disproportionately better relative to the cost.
It's simply worth it.
signed, Owner of A LOT of of LEGO kits/bricks _and_ clones.