Most days in this column I give you five of the world's worst stocks, inspired in part by Keith Olbermann's nightly news show Countdown, which features his list of the "worst persons in the world."

There's another segment of the show I find equally entertaining. A segment in which Keith names the "world's best persons" for their deeds and misdeeds, as it were. Today we borrow from that segment.

United Airlines parent UAL (Nasdaq: UAUA), which I earlier named the "Worst Stock for 2008," is today's best stock in the world. Here's why.

  • Oil won't stay $100 a barrel forever. Maybe oil won't go to $50 a barrel as UAL had suggested in its reorganization plan submitted to the bankruptcy court in September 2005, but do you really believe that it will stay above $100 forever? I don't. And, even if it does, Sir Richard Branson's Virgin Atlantic has shown it's possible to replace jet fuel with biofuel. Were United to follow suit the profit potential could prove enormous: UAL produced more than $1.4 billion in free cash flow in 2007, even as fuel prices rose 25%.
  • Incumbent unions haven't performed for employees. United has long battled with its unions. Calls for new leadership on both sides have mostly fallen on deaf ears. No longer. UAL's mechanics yesterday voted to replace the Aircraft Mechanics Fraternal Association with the Teamsters. Finally -- a new voice in a broken process.
  • The Feds appear ready to allow airline megamergers. All carriers are suffering. Discounters such as Southwest (NYSE: LUV) are facing maintenance problems similar to those plaguing American Airlines parent AMR (NYSE: AMR) and Delta. And yet there's good reason to believe that, with profits way down, the Feds would rubber-stamp a deal between Delta and Northwest or, similarly, a long-rumored United-Continental (NYSE: CAL) combination.

Upgrade me!
There's also the revenue opportunity. Most airlines, save for JetBlue (Nasdaq: JBLU) and the chums at Ryanair (Nasdaq: RYAAY), have failed at upselling in-flight services or better seating. United is the rare exception. Its "Economy Plus" cabin is for sale at a slightly higher rate than basic coach, and some of those seats do, in fact, produce revenue via cash upgrades.

But United should be flying higher in this area. Once onboard, you can't buy Economy Plus seating, even if that part of the cabin is empty. Dumb. When is a passenger more likely to pay to upgrade? When he's at a computer? Or when he's about to spend five hours between two strangers on a sweaty flight to San Francisco? But this is easily remedied, and I expect it will be shortly.

So, even though my UAL call -- had it been a short -- would have given me a 35% profit as of this writing, I say "Enough!" I take it back. UAL is no longer the worst stock for 2008. It is today's Best Stock in the CAPS world.

(Then again, it is April 1.)

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I'll be back tomorrow with a new round of stock horror stories. Meanwhile, check out the Motley Fool's new homepage.