Mr. Meat , a Japanese style Hamburg place I went is good and busy, and good lunch specials at NT$160: Near the Kao Culture Centre on the southside. Went for lunch, a mix of students and office ladies. Good meal, best in this city. Taipei has many more choices I think tough.
Good newer place, has Japanese style pork burger and Aussie style beef burgers (They lived in AU for a while). I saw very good google rating and it was good for me,