For the used bikes, are you considering bicycle size? If you get a bike too large or too small to get comfortable on, a killer deal can quickly turn into a waste of money.

Any of the bikes you listed by model would do. My personal direction (if the bike was the right size) would be the Sirrus Elite at that price. If the budget is an issue, the Trek would be a good choice too.

Check any out that look interesting, and the right size, then test ride it and see if it speaks to you.

The brands you listed are fine... just avoid people who try to sell K-Mart and Walmart bikes at the same prices.