Another perspective is go 51/49 (CEO 51, CTO 49) just so that later down the line you can resolve any "deadlocks". With 3 founders you'll never have this occur, but with 2 cofounders you will.

Remember you'll make a 10% employee/advisor pool and probably 10% to an Angel/Seed, making your 51% to 49% become 40.8% to 39.2%

By the way, we're all assuming that you'll both be committing to this 100% and full time. If not then a 50/50 split isn't right