They will make appointments based on the following
1) Ensuring that they will get through the Senate (historically, after Robert Bork was shot down in 1985, the president has been very careful in his selection as to ensure not to lose face).
2) Will appease their base (Since neither the GOP nor the Dem platform holds constitutionalism as it's primary cause, you will see slants of social conservativism or socialism with either candidate).
3) Payback for campaign or personal work (as evidenced by GWB's attempt at putting Harriet Miers on the pulpit).
They will not make appointments based on the following
4) The Constitution
Since the scope of my political beliefs don't encompass 1 through 3, then neither will make good appointments.