Right now PhotoBulk but Eltima Software is on sale for $6.99 down from $9.99 on the Mac App Store and it's probably some of the best money that I've spent on any app on my Mac. If you like editing and adding watermarks to your photos, check this awesomeness out! Other features include: Resizing, bulk renaming, optimzing and renaming, it also supports JPGs, GIFs, PNGs, BMPs and TIFF. Of course this wonderful app is available on Windows too. There's also a free version available at the Eltima website. Cheers!