Mark hates Adobe Reader and has removed it in favor of using FoxIt. Leo says rightfully so! But he's concerned about security in FoxIt. Leo says that FoxIt has different issues. But with everything coming off the internet, it's a heck of a challenge to protect against it. Bad guys have moved on from trying to hack the operating system and are now going after third party software like Adobe reader or FoxIt. But since FoxIt has a smaller "footprint" on the internet, it's less risky. It still pays to keep everything up to date just in case.
There's other choices like NitroPDF, Cute PDF, PrimoPDF, and Sumatra. Not safer, just less used. There's a great list over at AlternativeTo.net - http://alternativeto.net/software/adobe-reader/