Which LaTeX installation would you recommend using on OSX? Ideally I'd want the installation to contain as many packages as possible as I'll be using my Macbook offline mostly.
Have a look at MacTeX. It should fit your needs as you can choose between different distributions which vary in the amount of installed packages.
I would like to bring to the attention of those of us, who—for whatever reason—like their TeX distribution minimal, the BasicTeX by Richard Koch. It is based on TeX Live, weighing measly ~90 MB.
(I realize this answer is pretty much the opposite to what is asked, but given only the title and the tag, I thought it would be good to mention this)