whichever cheapest. guess what, car still going strong after 6 years. my 64 chevelle 400 sb lasted 15 years on cheap 10w30 and didnt burn a drop of oil the day i sold it after 210k miles on it. People put way, way too much preference into oil. even the most generic oil, your engine, providing its a decent designed one, will outlast most every other part in your car, not to mention most people don't keep their cars beyond 10 years.
When i went to NW mechanic school, had a professor do various tests on different engines with different oil and even one with drained oil so we could study the results. Amazing how long an engine can run with no oil.
you guys can think whatever pleases you, but imo, its pretty stupid to spend much on fancy oil. Your goin to replace and go through far more other parts on a car than you will your engine, and likely tranny for that matter too. Why waste more money on oil for a car most of you will probably trade in or sell in 5 or so years anyway? makes no sense to me. after so many miles, everything else on car is about junk anyway. be it weather stripping to tie rods, then they get rid of it or fix it, yet all that time the oil didn't mean squat.