One of the main issues that the Convention faced was that of representation. Bigger states (like Virginia) wanted a representation in Congress according to population, while smaller states opposed this since they feared their smaller population would mean less representation and eventually being ruled by the more populated states.
Another main issue was the Federalism vs. Antifedarlism issue. the federalist representatives were in favor of the idea of a somewhat "big" government to rule over the rest of the states, while the antifederalists opposed this "big government" and preferred a smaller more local government.