I really like Banshee, but I was shocked to learn she was at a mere 0.53% usage on last year's published stats. I'm also really fond of Yareli and Gyre.
Zephyr is probably my top used frame, very slept on, whats not to like about effective immortality and with subsumbed spectrosiphon, infinite energy and crit bonus. I still run the projectile speed mod too, since it makes shotguns stronger and boltor/nataruk hitscan.