I just picked up the awesome new PDFpenPro 6 (Mac App Store Link) from Smile. It’s a superior alternative to Acrobat or Preview on the Mac. I bought the Pro version because it does quite a few things more than the regular version, and right now it’s only $10 more. If you do any kind of PDF mark-ups, editing or form creation, you shoud pick this up while it’s on sale for the next day or so. There are two versions - PDFpen and PDFpenPro. The pro version allows you to create form fields that can be filled out directly in the PDF. I use this on my Mac and I also have it on my iPad.
One of my favorite things about this tool is how easy it is to insert my signature, and sync everything over iCloud to my iPad for documents on the go. It also has a great ink engine in it for sketch markups, which makes it a great tool for architectural designers.
If you get it now, both versions are 50% off for a couple of days only. After that the price goes up, so take advantage.
Get it at the Mac App Store. I prefer that verison to the regular one because there’s no serial number to store, updates happen in a more automatic way, and it has the iCloud sync option. If you go with the regular serialized version from their site, which is the same special discounted price, you don’t get iCloud but you can use Dropbox for sync.