There appear to be three alternatives being bandied about: the Boehner bill, the Reid bill, and failure. Maybe something else will crop up if the first two of these die. The Reid and Boehner bills both toss out the President's demand to raise taxes. The Boehner bill has what is now scored as $900+ billion in spending cuts, with mechanisms for further spending cuts and, just as importantly, tax reform later on. The Reid bill has mostly phony spending cuts, including a drawdown of spending in Iraq and Afghanistan that is already in the spending baseline. The Boehner bill gives only a short-term increase in the debt limit that will last for only 6 months or so. The Reid bill, on the other hand, raises the limit by enough that the issue shouldn't come up again until after the 2012 election. Apparently Democratic senators from red and reddish states do not want to be arguing for tax increases just before a bunch of them are up for reelection.
Focusing on fiscal sanity rather than politics, the Boehner bill is clearly superior to the Reid bill, while the Reid bill might or might not be better than failure. Boehner does something about spending and promises concrete processes to achieve more later, unlike the bipartisan Gang of Six plan from last week, which wasn't tied to the debt limit. Reid does next to nothing about spending and promises nothing down the road. It's seems to be nothing more than political cover. Obviously, all plans are designed to provide political cover, but not all of them also achieve something.
Update: Here is Douglas Holtz-Eakin's take, which sounds about right:
The plans are quite similar. Indeed, the best way to think about the Reid plan is that it is simply the Boehner plan with fake cuts (largely war spending) added on. Put differently, executing the Reid plan is the same as executing the Boehner plan and then adding an unrestricted debt limit increase on at the end. Since so-called “clean” increases are a signal to markets that the U.S. cannot address its fundamental problems, this is extremely dangerous and undesirable.
