[Vikesrock]

This question probably needs a little (or a lot) of clarification before you'll get the answers you want.

EDIT: Okay now that this is fixed I can provide a better answer. In my opinion none of these are "better" or "more vital to the success of a robot" than any other, there are correct applications for each of these types of fastening and using each fastner appropriately is the real key. Zip-tying the entire robot is impractical as is welding on your flag holder, for each spot you need to connect two items assess the situation and choose the best method that fits within team capabilities (welding may be out for example)