The biggest jackpots get the most ticket sales, according to the organizers of the large lotteries.
That's fine for them, but it means you may have to share your prize with others. I recommend you stick with smaller prize games for the better odds, but there's no harm in playing the big jackpots for the many secondary prizes either.
Here's the top 6 jackpots - and you'll notice there are only two games, Mega Millions and Powerball:
$640 - Mega Millions – Friday, Mar 30, 2012
$390 - Mega Millions - Mar 6, 2007
$380 - Mega Millions – Jan 3, 2011
$365 - Powerball – Feb 18, 2006
$340 - Powerball – Oct 19, 2005
$336 - Mega Millions – Aug 28, 2009