I like screws if the WF plate thicknesses are thin enough for that to be feasible. Advantages:
1) Least cost, I suspect, in many applications.
2) Bolts will have more connection slip before everything engages.
3) Welding cold formed material without burn through requires special skill.
4) As a general principle, weaker materials like wood and thing sheet steel tend to favor smaller scale, more frequent fastening.