I'll go with Josh Johnson. Gil Meche is underrated, but Johnson pitched quite well for a post-TJ pitcher last year. Johnson's upside is good enough to give him the edge here.
Johnson tossed: 115 inn. in '04 150 inn. in '05 160 inn. in '06 35 inn. in '07 90 inn. in '08 and you would expect them to hold him down to 150 max this yr.
I'll take Meche & the 200 innings at the same ratio's, or better, as Johnson.
From June on, Meche went 11-4 with an ERA in the low 3's and a WHIP around 1.25, while averaging almost a K per IP. He's quite possibly the most underrated and undervalued SP in fantasy baseball. Throw out April and some might have been talking Cy Young candidate (reaching, I know).
Meche's numbers across the board were better than Johnson's if you toss April. While JJ might have a higher "upside", I'll take Meche and steady production on a Royals team that is poised to surprise some this year.