I'd probably vote for Bloomberg over Sanders if it's Sanders vs. Cruz/Trump. But such an election would also be awfully dangerous. As Paul Krugman pointed out, Bloomberg would probably pull more from the left than from the right, and Trump could win on a modest plurality of votes. I tend to line up pretty well with Bloomberg (liberal on social issues, moderate on economic issues), but I'd like to see exactly what policy positions he pushes.
Incidentally, I worked for Bloomberg's company for a summer. And, if Bloomberg runs, I will have worked for two companies run (at some point) by presidential candidates.