It depends on what you are looking for. If it's straight wins, Lidle is a good pick, because he gets excellent offensive support. However, his ERA is at like 4.90, so that can be a bit of a drain. If you want ERA and K help, have a look at Ischii. He gets lots of K's and keeps his ERA down(and pitches in a pitchers park), but also walks way too many batters, so he will drain your WHIP. Kinney and Johnson have respectable K, ERA and WHIP numbers, but play for bad teams that have lousy bullpens and lousy offensive support, meaning that you can't expect many wins. Webb has still only had like 3 major league starts, so I'm not sold on him, and when all the DBacks' starters are back, he's the odd man out and will have to go back to AAA. Using rookie pitchers in fantasy leagues is a risk I always like to let other owners take.
Brandon Webb should top the list. Everbody is raving about his sinker, saying it is like trying to hit a shot put. If you can grab him quick and start him for the SD game, do it. He will remain in the rotation when Johnson gets back.
I think Kinney is intriguing, but MIL is not a good place to pitch. I don't know enough about him at this point, but I am keeping an eye on him. If Webb is available, people in your league are slow, and I think they are not aware of Kinney at this point either. I'd leave him on the wire. Forget about Livan.
I'd grab Ishii or Lidle after Webb, both require monitoring. Ishii had some good games early last year, but his WHIP was awful and he wound up hurting more than helping. Keep an eye out for that. On his game he is a better option than Lidle, but if his WHIP soars it's over. Lidle might be a safer bet to hold some type of form the rest of the year.
* Steroid induced record
How is Webb going to remain in the rotation when Johnson is back when they already have Johnson, Schilling, Kim, Dessens and Batista? Unless they wind up trading Kim away for a power hitter, which has been rumoured, there is no spot for Webb and he'd have to go to the bullpen or AAA.