With some aftermarket strut bars, I've seen that the connecting bar can be removed to work on the engine instead of removing the entire unit (ARC & Cusco??). If the aftermarket bars are practically the same as the stock, minus being adjustible, I think I would go with the aftermarket strut bar just for convenience (2 bolts vs. 6 bolts & 2 nuts).

 

If the bars can be removed, without having to take the mounts off, wouldn't that be ideal, because the n you can weld the mounts in place, but still remove the brace when you need acces. And that would be the setup that would give the least amount of "play" (except for a solid piece)

 

but keep in mind the bar is still being bolted to the brackets, which is still less than ideal from a pure "stiffness" standpoint.

I suppose the welded brackets would be better - by how much? I would doubt you would ever be able to tell, and now you would have done a mod that cannot be reversed.