THIS is the tough one to call imo.
It's a toss up between:
Selina for being a nonstop pain in the ass and frankly vulgar on the show, off the show and - if reports are to be believed - behind the scenes of the show. Complaining almost non-stop, sometimes not putting in any effort at all. She was downright bad.
Charleine for being far too much of a loose cannon with her emotions. Yes, Charleine certainly had some strong moments and when she threw herself behind what the team were doing it normally went well. However, she so often let her emotions get the better of her (David in the boardroom, Richard in general, Selina in general, etc.)
Natalie for being completely useless in absolutely every single regard imaginable - including helping Vana in the final.
Mergim for just generally seeming like a bit of an idiot all round and generally incompetent at business.
Think I'm gonna have to go Natalie on this one.