I like 十八梯 (shi2ba1ti1) http://www.18t.com.tw/html/contact.htm
No English on the website, it is on jing1cheng2 Rd, corner da4ye4 Rd.
If you like really hot and ma, get the fish pot. With loads of Sichuan peppers. Not cheap though.
Little Fat Cow is really good, too, but it is more of the "Mongolian" type. Not cheap either.