Hallo Hallo
Bipolar is Ok , but how to get rid of base current? Anyways it depends , if u have bicmos technology.
Generally Take mos as Diff pair and try to dimmension it , so that it has enough gm/B.W/ 1%matching error. Don't forget to concentrate on ur current load(u have to consider 1% matching error).
Most imortant thing is , how you do ur layout? Try to fetch the best one for ex: Commmoncentroind Layout technique for Diff pair layout..
There r somany other ways to remove offset , ex chopping techinue(Auto zero technique) but if u want to do with simple OPAMP. these r the parameters which u have to consider.
Best of Luck