Obviously, it all depends. This is my (limited) view:
From features respect, Green Plum.
Popularity with a bit of hype, Netezza.
Matured and well respected, Teradata.
With existing database integration, Dataupia.
Largest implementations:
Teradata: 72 nodes (two quad-core CPUs, 32GB RAM,104 / 300GB disks per node) and manages 2.4PB.
Greenplum: Fox Interactive Media using a 40-node, Sun X4500 with two dual-core CPUs, 48 / 500GB disks, and 16 GB RAM (1PB total disk space)
Source: Vertica’s Michael Stonebraker!
