I am no expert on the matter.. But I've done some research and watched videos on both. From what I understand...
Front Mount
Pros: Direct airflow across most of the intercooler face (rather than funneled via hood scoop), better cooling, more room for a larger intercooler, looks badass
Cons: More complicated installation process (rerouting charge pipes/tubing, etc), more expensive than top mount
Top Mount
Pros: usually a 1 for 1 replacement of stock intercooler, better cooling than stock (usually a bit less efficient than front mount), less expensive than front mount, easier installation.
Cons: not as badass looking unless you open your hood, not as efficient/less gains than front mount, less effective cooling because a top mount is within the engine