I'm also looking for the best calendar app, but I really think the perfect app doesn't exist yet. Super Calendar came so close. It was beautiful and customizable and I had no complaints...... Until I tried to edit an appointment. It's a calendar app that can't edit or delete appointments? What the heck?
Cal can edit and delete etc, but it really doesn't do anything more than the stock calendar app (in fact it does a little less: no ability to create, edit, or delete recurring events) and just didn't seem worth it.
I've yet to find a calendar app I'm willing to pay for.