Nobody mentioned Eve yet?
Snoop Dogg ft. Eve - Ready 2 Ride - YouTube
There's an MC from England called Lioness, she's well known here, she is very, very hard:
EMG - Lioness - All Black Winterness - YouTube
Lady Leshurr is very good as well, really sick:
SB.TV - Lady Leshurr - YouTube
Her verse on this was sick as well:
http://www.youtube.com/watch?v=Pr_Tbv5wMI4