I find it a bit ridiculous that one (meaning a local who can speak 'accented' Mandarin) would try and learn the BJ accent....but that's China.

TW accent is most natural for me, but that's because I learned most of my speaking ability there and had my original exposure there. It sometimes shocks the locals in the Mainland because just about every laowai they meet who can speak Mandarin has a textbook BJ accent.