You like a table makes little sense in english. Tables don't differ much one from the other, so if you like one table its assumed you like all tables.
You like tables is better. Although this still don't really make sense because there's no real reason why anyone would dislike tables.
Cases, explained: http://www.nthuleen.com/teach/grammar/nomakkdatexpl.html
Ein/eine/eine+x with cases, explained: http://german.about.com/library/blcase_sum.htm