As to the original question, if you are starting from zero and you want a means of avoiding critical shareholder deadlocks, you can split 45/45/10 with the smaller portion going to a party both founders agree will be impartial. This person can be the initial angel, or perhaps a minor founder who accepts a smaller chunk in order to maintain his dayjob.

You can also maintain 50/50 splits of ownership but still break executive deadlocks via a third vote by mandating a third seat on the board. This won't help fundamental shareholder deadlocking, but disagreements rarely go to the shareholder vote level.