How to fix front door that needs to be pulled for latch to open?
This is likely related to alignment of the latch (the mechanism that runs through the edge of the door, from the lockset to the door frame) with the strike plate (the metal plate attached to the door frame which guides the latch plunger to its "latched" position).

Look closely at the strike plate for signs of misalignment; like heavy off-center scratches in the area where the latch "strikes" the plate. Look for indications that the latch is not lining up with the hole in the strike plate.
Sometimes this happens due to settling/movement of the house due to seasonal changes, and can be remedied by filing the hole in the strike plate. Try removing the strike plate and watching how the latch behaves, at the edge of the door, when closing the door.

There could also be one or more of numerous other problems: loose hinges, loose lockset screws, warped jamb, warped door, worn out latch, worn out lockset, wall movement, etc. Start troubleshooting and eliminating possible causes until you find what the problem is.