Do you mean which browser? eg Internet Explorer, Chrome, Firefox, Safari etc etc? I think that's a matter of choice and you can have more than one installed at the same time (I switch between IE and Chrome).
I've seen two ABers, both of whom are known to have superior IT knowledge, each say I use Chrome wouldn't touch IE with a barge-pole or I use IE wouldn't touch Chrome with a barge-pole so what is one to do!!