The detailed plan for Barbarossa was drawn up by General Alfred Marcks, and I think it was the best plan the Germans had with their available resources. This plan identified Moscow as the key target, with Leningrad a secondary target.
The problem was that the Fuhrer deviated from the plan with his constant interference with day to day operations, and in my view the deviation was fatal.
However the biggest mistake of all was attempting Barbarossa while Britain was still in the war. All German resources were needed for Barbarossa and they were already being dissipated by Churchill's dispersion strategy. For example one of the best panzer generals, Rommel, was in Africa, with substantial Luftwaffe resources in the Med, facing Britain and in the Atlantic.
Had Hitler followed Marcks' plan with a defeated Britain I think it could have succeeded, especially if it had been launched at the end of May rather than late June..
''Give me a Ping and one Ping only'' - Sean Connery.