Lester has many teams lining up to get him, and a decision is coming soon. I already wrote an entry on Lester's options, so here I will just briefly state those teams in order of how likely I think they are to sign him.
Dating back to last year in extension talks with the Tigers Scherzer's signing strategy has been to wait it out, declining a reported $144 million offer. Scherzer's agent Scott Boras is generally a big fan of waiting on contracts. It is a risky but potentially rewarding strategy. Scherzer will almost certainly start receiving contract offers immediately after Lester chooses a team. Scherzer is by far the most valuable pitcher on the market, with a 2014 WAR of 6.0, much higher than Lester at 3.6 or Sheilds at 3.3.
Other Free Agents
These are the "big three" starters on the market, but the many other options include: Francisco Liriano, Jake Peavy, Ervin Santana, Brandon McCarthy, Hiroki Kuroda, and more. The most interesting of these options in my opinion is Francisco Liriano whose up and down career has been slightly more consistent in the past to years with 3.o WAR in 2013 and 1.5 WAR in 2014. Those who miss out or can't afford any of the "big three" can certainly go after one of these pitchers.
Open to Trade
Jeff Smardzija was the first pitcher to be traded at the meetings, but more will likely come soon.
Cole Hamels has had numerous rumors circling around him this year. The most likely option for trade is the Red Sox, who will be trying to fill two to three rotation spots (depending on if they are comfortable with Workman or Webster in the rotation), with rotation spots to fill and eight outfielders to potentially trade, a trade sending outfielders for pitchers is a must for the Red Sox. If Hamels' price is to high for the Sox they are also rumored to be going after the Tiger's Rick Porcello and the Padres' Ian Kennedy. It is also possible that the Red Sox trade for two starting pitchers if they strikeout in the free agent market.