If you want to stock up on post-2007 blends just in case, I share jack's view that TobaccoReviews.com is an excellent place to start. All of my favorite blends are rated around 3.5 or higher there, so in my experience, even though tobacco preference is somewhat subjective, the reviews on that site are a great guide. Any blend with a lot of reviews and a high rating, you should be able to easily re-sell / trade if you don't like it.
However, I will say that if you have to ask what tobaccos to stock up on, you have not yet developed your preferences enough to begin stocking up (unless of course, you just want to secure the popular post-2007 blends to try). I've been smoking occasionally for several years, and have taken the pipe up full time (daily, or almost daily) over the past six months or year, and my tastes are still changing, though I am beginning to settle on a few favorites. I absolutely love Gourment English from Iwan Reis for an excellent mild English blend, and I like Dunhill Flake for a Virginia. However, these are both pre-2007 blends as I understand, so should not be affected by the deeming laws.
Of course, its your money and your cellar, so your mileage may vary.