There's no question that Briana has skills and attitude, but I'm not really a fan of her body. Her legs (and ass) seem dangerously thin, and I'm not a fan of fake breasts (especially if it's obvious they're not real).
In her prime, Jenna was an absolute goddess, and completely deserving of her Queen of Porn status. I don't think I've ever seen a better boob job than Jenna's. She genuinely seemed to enjoy her job.
I don't think they're very similar at all, to be honest. Not a difficult choice for me.