The best grade of steak is PRIME, followed by CHOICE, then SELECT.

Prime beef is the absolute best. It's produced from young, well-fed cows, and has lots of marbling (fat). Only 2% of the beef in the U.S. is labeled Prime, and most of that goes to restaurants. If you can get your hands on a Prime steak (they'll occasionally carry it at higher-end grocery stores like Whole Foods, or you can order it online here) and are willing to pay a little bit extra, go for it. Otherwise...

Choice beef is widely available and still pretty high quality. Just make sure to look for the steak with the most marbling (fat), since this is what adds flavor and keeps the steak tender during cooking.

Select beef is leaner and typically not as juicy and flavorful. It's also available in supermarkets, and it's an OK choice. But, this is Valentine's Day we're talking about. If cost is a big issue and you go for Select beef, make sure to cook with plenty of fat and baste with butter at the end.

(Yes, there are lower grades of meat, but these are ground, chopped, or used for pet food.)