i've always used Castrol synthetic blend, i wouldn't go to say its the best, but as for the use its great, i can't afford royal purple since i change my oil once a month. my dad uses dino castrol, and he does 130 miles a day, he changes his oil every 3k, he has a 2001 toyota echo 1.6 dohc and he's @ 180K miles to date. his oil still comes out just as clear as he puts it in, its freggin crazy.
i would ask you what your use is, because if you have just a daily commuter, a less expensive oil will do just fine, usually a more high performance motor is going to require something really good. i guess what i'm saying, is if you haven't overhauled the motor and tweeked its specs to run higher hp, i would doubt if you need such a performance oil. just my thought, i could be wrong, but just thinking logically.