I would go for +1 (from my short search the 20's only come in 9" or 10" widths). The +20 is a higher offset (by 1mm if a 9" wide wheel) than stock, and that wont clear the tires that I suspect you'll run.
It's all in personal preference man, I like the 22's on my truck, I'm not quite sure why CaptJohn had balancing issues but he's a very small minority of people who have. No offence Captain, I think ou had a bad tire guy though. I had the Chrome Clads on my truck and went with the 22's and the ride quality is damn near the same even though the sidewall is smaller in comparison. I run a 285/45 and have no rubbing issues but I wouldn't go much wider up front or you'll be rubbing the sway bar.