If they had played the same amount of games, Happ would have a much better fWAR than Beni. Also, Beni's abbertation year of 2018 is really pumping up those numbers. If that Beni doesn't ever come back, Happ is definitely the better player.
Happ has a better career OPS and WRC. Happ is also a much better fielder. Beni is adequate in LF. When Happ plays LF, he's been great.