You forgot JBossWS :-)
On the
SOAP side, I think Metro (which includes the JAX-WS RI) is probably the most widely used one, followed by Axis2.
For REST, I think it's hands-down Jersey.
I'd start with REST and Jersey, just to see how easy it is, and only graduate to SOAP if necessary. SOAP is more complex (more capable, too), and is in many places being phased out in favor of REST. The
WebServicesFaq contains many useful links.