Four OE Bridestones with 15,000 miles on them, around half tread left, puncture in the sidewall of one.

Assume I don't really want to buy a complete new set.

Should I replace one with a new Bridestone RE040 ($230) or replace two with Falken 912s ($140 each)?

Is the replacing two strategy sensible, and if so should I keep the new tires on the rear or front?

Thanks.