You can find some websites with results from
benchmarking
with ECperf and in almost all of them Oracle AS is
better than any other App server. If you want to use
Oracle AS you better pick 10.1.2
The statements about higher hardware requirements is
simply not true, because every bit and piece of Oracle
AS
is separately installable and configurable so you can
pick and choose. Plus it will give you the opportunity
to cluster most of the components. Another good thing
about
OAS is that the HTTP server  is the standard Apache
HTTP server and you can benefit the existing wealth of
knowledge ,experience , support and stability of
Apache. Furthermore the Portal, Wireless, and Security
features that OAS offers is far more powerful than any
other App server. Last but not least, OAS is now a
part of Oracle Fusion Middle ware that is a whole
suite of products and tools that will give you much
more power and satisfies your every need for
enterprise computing.
And as Oracle has bought many other companies in the
past three years the best features of those industry
leading solutions are being incorporated into Fusion
with the hot pluggable concept (loosely coupled SOA
based integration).