In a standard league, I'd probably go:
Radke, Pettitte, Maddux and then Thomson.
Radke - will give good ratios, good win rate, and is clearly in an easiest division of the four...who wouldn't love facing KC and Detroit--at Comerco when away, no less--multiple times a year
Maddux - he'll get his, but I'm not sure he's his automatic 15 WIN self this year; the Cubs are just too unpredictable
Pettitte - probably has the highest upside of the four; it's just too bad Houston's offense has been lacking
Thomson - the NL east is a tough division this year, and the Braves offense is just too anemic thus far to merit Thomson any higher. How else can you explain Smoltz and Huddy not being considered among the elite pitchers thus far in the league (except among their fantasy owners, of course).