OmniFocus vs Things
The big GTD question on a Mac is Things or OmniFocus?
They are both very good, and I think which one is the right for you depends a lot of your personal preferences. It was a time in the middle where it was a very easy pick because Things used a shit load of time to get their sync act together.
Things is a little bit easier to get started with, while OmniFocus is a power tool. I have used both, multiple times over the years.
Things look a lot better. But it is a little bit too far in the eye candy over usability in some areas. It does for example drive me nuts that it takes noticeable longer to add a task to Things versus OF.
OmniFocus on the other side is a little bit more nerdy, and it takes a while to get into it. But when you do, it is a power users dream. It is awesome.