I've gone the natural route with some hits and misses along the way. The combo that seems to work for me is an strong dose of probiotics (a combo of good bacteria, I like Primal Defense from Garden of Life) and an herbal product called Envirelief from Jallie. It took a good week or so to kick in but they've seemed to keep my allergies under control this season.
As far as the best? That's a tough one because we're all different. I'm likedoodledog, Zyrtec stopped working after a couple years.