Strasburg is a no-brainer, even if Rizzo limits him at 190 IP. The K% and ERA/WHIP are so good, Strasburg + 40 IP of Waiver Wire scrub is still a top 5 pitcher (really! do the math!)
Price because his floor is higher and his chance of reaching a higher peak in 2013 seems more likely. Also, I love Rays pitchers because they pitch in front of Rays fielders, although that applies to Moore as well.
However, the cost of keeping is definitely worth mentioning here, especially if you're allowed to keep a player for multiple years, or there is an escalator cost attached to keepers. Ditto league size and whether you're trying to win in 2013 or 2014+. For instance, if I could hold Moore at something like $1 for another 2 years, didn't see myself winning next year, I'd consider holding Moore over Price (who is probably way more expensive). (Actually, I'd probably still keep Price, but it forces me to at least consider it).