I have fired both. I own 2 97B's and my buddies old duty-carry was a P220. I prefer the 97B for its recoil, precision, and ease of take-down. However, I am a big fan of SigSauer, and would love to get a P226 X-Five LW (9mm). I like the grip of the 97B also, as it is most closely related to a 1911 grip; the P220's grip is a big wide for me, which made a bit uncomfortable to fire at length. Also the 97B feels a bit lighter to me, allowing me to focus on my aiming a bit better. The price is drastically different also, MSRP is between $900-1100 depending on the sights you get. The 97 falls between $500-800 or so.
If you have any other questions about either let me know, I can tell you just about anything about either as I have fired both extensivily