my ideal three for you would be...

Prodigy - predictable roll in oil (mine is usually first out of the bag)

Mutant Cell Pearl -  used when a pearl needs to be used (awesome when the lanes are broken down) it is weaker than many think.  Weak on heavy oil, but allows me to play the same line as i started with on a fresh shot when i finally switch to it usually in the third game.

Reign Supreme - Gotta have a hybrid ball to help blend everything..or like JLS said, a go to ball!  

i take 5 balls but those are my top three when i need to put up scores, these are the least "conditional" balls, but the most "versatile" balls i own.

you bowl on med oil synthetics..the prodigy will love that for sure.  

for tourneys....and heavy oil or sport shots

i would add a assym. oiler for example invasion, virtual gravity, theory (i love the storm poured azo area check)

and to complete the low end of the bag a dark star from roto grip or a tropical heat will help with spares and shots with absolutely no oil.

this is my opinion im sure there are great ebo or 900g recommendations as well but i throw mostly storm/roto..hope that helps if you were considering anything from storm/roto.
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my arsenal..

http://s890.photobucket.com/albums/ac110/_billdozer/My%20Arsenal/