I do mine on top for a cleaner joint, on most motors the holes are large so wire is a bit sloppy in hole so top is best for me.
Another idea is to take a dremel to the tabs and cut across the hole so you left with a half moon makes soldering now very easy. HTH
MB Models Leeds,RC4LESS,Troy McKune
V-DEZIGN CR5 ,LRP SXX, CRC cells,