The form is great. Perhaps a slightly smaller footprint but this is very close to a "perfect" form.

As to the finial, there are a number of "schools of thought" there. One of them dictates that the elements of the finial decrease in size from bottom to tip. Another suggests that if you create an imaginary line that continues the sweep of the form all the way to the tip of the finial, all of the finial elements should be tangent to that line. Your finial has not followed either of these. The replication of the form overpowers the rest of the finial elements and immediately pulls they eye to that point rather than letting the eye arrive there by following the "flow" of the form up into the finial.

I also think your finial has "one too many" elements. I would eliminate the ball, Increase the size of the cove and reduce the size of the "embellishment". Both of these would serve to bring the embellishment down and allow you to elongate the "onion". From there up, you're looking good.