If you can find one, I would say Tsunami.
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The only difference between Genius and Stupidity is Genius has its Limits

I don't know anything about Lane #1 balls but please read this great definition of what a bench mark ball is written and posted by charlest previously on the LM/L forum.  Great definition and should be taken to heart by those that REALLY want a bench mark ball for any mfg. IMO.

Benchmark balls are medium overall hooking balls, with medium length, and have a medium backend. They are used on medium oil patterns and they are defined by their arcing breakpoint. They are used to tell the bowler immediately what kind of pattern they are on when all the usual factors are unknowns. They also tell the bowler if they need a stronger or weaker ball and where to play the lane.
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Scott

coach, this ball is retired, but there are still some around. If you can find one, I would highly recommend this one. The original pearl uranium.

http://www.lane1bowling.com/balls/uranium.html
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Righty
Think about it!

It is impossible to govern rightly without God and the Bible. - George Washington

Any of the berrys other than the cranberry make great benchmark balls.

IMHO the PK18 coverstock cannot be beat in consistancy in reaction. It makes for a ball that is very easy to read. That combined with a core that likes to roll makes a great control/benchmark ball.

THe Tsunami hands down...

Several of the balls mentioned here have been out of production for some time now and are very expensive to find NIB...

As far as the EU and BCB I would consider them allot stronger then the Tsunami and therefore not very good when the conditions are less the heavy.  THe Tsunami works well on all shots except the extremes and is a very smooth control ball and therefore the best benchmark ball IMO..