The advantage of anterior approach is lower risk of dislocation and less disruption of muscle attachments. If they use imaging or robotics for placement at surgery, it is very good. They have about 15 years of experience with it and it does have a good track record for the surgeon comfortable with it.
My husband has had both - anterior for the primary and posterior for the revision 1 month later due to fracture, then twice more for wash out and explant due to infection. He says pain-wise they were similar, but most say anterior is less painful. He did have a temporary foot drop after the last surgery. However, due to excess weight, he felt the incision through the groin (anterior) did not heal well (necessitating re-closure) and likely seeded the infection that popped up at 2 months from the original. While he was fine with the anterior approach initially, in retrospect, 5 surgeries in and still waiting for another hip, he thinks that he would have gone posterior because of his belly weight.