When once asked about his best play, Willie Mays said, "I don't compare 'em, I just catch 'em." I feel the same way about hardware vendors; they just sell computers. But for many people, discussions comparing vendors can quickly get ugly. You'd think these people worked for or had huge stock holdings in their vendor of choice. More often than not, it's just an issue of comfort. If you've been a DBA for the past five years on platform X, then you'll often argue why it's the best platform out there, regardless of reality. We all do it; it's just human nature.
Nonetheless, there is a very clear hardware vendor that is, arguably, the best choice for building an Oracle data warehouse, and that's Sun. Let me explain.
First, Sun easily meets the basic hardware requirements. Sun's Enterprise 10000 is an SMP machine that scales to 64 processors. Moreover, the HPC 10000 can be clustered to 1024 processors. Plus, Solaris is a fairly robust and proven 64-bit version of the UNIX OS. And let's not forget the UltraSPARC, Sun's latest generation of the proven and potent SPARC CPU architecture.
Second, there are plenty of DBAs, developers, and system administrators familiar with Sun and Solaris. So, staffing the data warehouse project will be easy. From my experience, many DBAs and developers have worked on all the big three UNIX versions: Solaris, AIX, and HP-UX (and increasingly now, Linux). So, Sun and Solaris should not surprise or offend the critical masses.
The main reason to pick Sun is that's where Oracle develops, so new versions and patches come out on Solaris first. In OLTP environments, DBAs tend to wait six months after a patch is released before installing it. That's fine for OLTP database needs, but data warehouses are different. Data warehouses are huge, with tables in the hundreds of millions or billions of rows. You will experience lots of Oracle problems with databases this size. Whether it is parallel query process failures, incorrect explain plans for partition eliminations, or corrupted bitmap indexes, count on encountering lots of Oracle problems and needing patches as quickly as possible.
Just as a point of reference: I did my last data warehouse on an HP server. I also do not own any shares of Sun stock. So, I honestly do not feel like I am making this recommendation based on any personal prejudices.