I spent many days searching for a theme that was attractive and flexible before trying out Circumference. Of the hundred+ themes I tried - having reviewed many more - only Circumference ticked most of the boxes (it ticks them all except for “support for RTL” which we may need in future).
Having installed Circumference-lite and adjusted things to be almost what I needed without too much trouble (despite being new to WP), I decided Circumference was the way to go. Support has been as good as the theme - my question to the support forum was answered quickly and helpfully.
A lot of work has gone into making the theme robust and flexible. I was so impressed by the theme that I decided to bite the bullet and buy the premium version even though I'm still evaluating WP as a CMS. The premium version is worth every penny - the video tutorials and additional features make it possible and easy to further polish things and support remains excellent.
Highly recommend - simply excellent.