The battle for top sales people and engineers is extraordinary in Silicon Valley and New York City – even if the employment numbers in the rest of the country remain anemic.

Job boards are everywhere these days; tech companies are paying tens of thousands in signing bonuses and even more to keep key employees; and tech companies are having to spend millions to buy small startups just to get their engineering talent.

But who is winning the battle?

TopProspect, a crowd-sourced headhunting startup based in San Francisco that pays users a minimum of $6,000 if they successfully refer a friend to a job, thinks they know. They ran the numbers on their members and their contacts to see who had switched jobs in the last two years.

The big winners?

Well, if you look at the number of people who left compared to the number who joined, you can see the power of stock options at hot companies.

Twitter hired nearly 11 employees for every one lost; Facebook and Zynga averaged about eight new hires for every defection, while LinkedIn clocked in at +7.5 and Groupon at +3.9. Other big names fared less well: Intuit hired 1.2 for every one lost, the same ratio as Google. Meanwhile others are bleeding talent: eBay hired 0.8 people for every person who left, Microsoft got just 0.4 and Yahoo 0.3 (not surprising, given Yahoo laid off hundreds at Christmas time.)

In terms of raw numbers of new employees, Google, Facebook, Microsoft, LinkedIn and Apple were tops – not surprising given their size. But some of those same companies were also on the list of the top five biggest losers: Microsoft, Yahoo!, Google, eBay, and Amazon.

As for the data set, Top Prospect says it covers its user base and their networks, which comes out to about 2.5 million profiles, that are largely Bay Area-focused. So while it's no census, it's a pretty good snapshot of the tech industry.

Graphic: TopProspect Job Graphic, Courtesy TopProspect*

See Also:- 5 Reasons Silicon Valley Might Stumble Coming Out of Recession