They're both totally correct.
The only reason to use the "with whom" version is if you're trying to avoid ending with a preposition ("with"), which is one of those archaic grammatical rules that still clings around the edges of formal English even though nobody actually talks like that anymore. Only the stuffiest editor would insist on "with whom" in a publication, and for anything less formal, the rule is entirely optional.
Arguably, there never was such a rule at all -- at one time, there were a number of educated people who tried to make a bunch of special rules for "proper" English that were designed to make English function more like Latin, which they considered the best language. "Never end a sentence with a preposition" and "never split an infinitive" are two of those rules.