After running the BFGs for about 6 months now, I'm not convinced that the Michelins are any better. Just my opinion, but I won't buy Michs again.
The facts are that there are different tires for different uses. The OEM tire, and unquestionably the best all-around tire for the Viper, is the Michelin PS2. It is designed to handle just about anything you can throw at it, whether it is track, autocross, wet conditions, etc. Others, like the Kumho XS, are more purpose-built with softer compounds for top dry traction. The BF Goodrich has a slightly harder compound that offers good wet traction but may not grip as well in track situations.
So you then have to ask yourself what your own personal driving style is. Many of us will never see the track outside of parade laps, nor do we push the traction limits on our weekend cruises. After that it comes down to your budget and how long you want a set of tires to last. The softer the compound the less likely they will last even 15,000 miles.
There are some great deals on tires out there right now including Kumho, BF Goodrich, and the vaunted Michelin PS2. As Jon pointed out, you should
never run with mismatched tires (like wearing a different brand of sneaker on each foot), nor those that are six years or older - even if they have minimal miles. Now is a great time to be contacting your club sponsors to see how they can help.