Technically, the best plugs/wires are the ones you get from the dude in the
parts department at your local Authorized Ford/Lincoln/Mercury dealer.
In reality, any plug that isnt $0.10 will work :)
Also, I'd say if you just do city driving and not that much, and don't put
more than 10,000 miles on in a year, yes, changing plugs every 25,000 or
2.5 years is a good idea.