I shouldn't spend any money, so I'll only name a long shot item: Harrison Striper Titanium, the colourful ones that are 70ish grams...
I love it in my XCG4 4W and would be real sad if I ever broke it. That's my go-to tee club for 250-280. I should really be using a heavier FW shaft but this one just plain works when my tempo is good. Unfortunately I have no idea what flex it is.