I've had the pleasure of getting a couple rad pieces at Frith Street Tattoo by the amazing Valerie Vargas. The wife has work by Emiliano Liberatori, and my brother grabbed a piece by Oliver Peck during one of his guest spots.
The entire crew are outstanding artists. I hope to work with Stewart Robson and Stefano C in the near future.
Soho also boasts having Diamond Jacks and Tattoo13. Where do you go and recommend some artists?