I'm investigating potential hosted SQL data warehouses for ad-hoc analytical queries. I've read quite a bit about all 4 of these technologies and their high-level tradeoffs, but I'd love to get people's first-person accounts of the pros and cons of each.

Dimensions I care about: query performance, load performance, cost, stability, maintainability, features (e.g. views, UDF), limitations (e.g. concurrent queries, schema restrictions), and all of these at scale.

If you've used any of these and have thoughts, would appreciate hearing them, thanks!