Personally, assuming everything else is equal, I would opt for the position which allows me to learn some new technologies. I think that it would (1) make the job more interesting and (2) make me a more well-rounded tester and hopefully therefore more marketable (though I have no scientific evidence to prove the latter).
"Any sufficiently advanced bug is indistinguishable from a feature." -Bruce Brown
Web testing can be broad. If you are doing click, click, click type of web testing then move forward to client/server testing. If your web testing experience has to do with web server configuration then both of them equally important. Web Server is still evolving .. just my personal opinion. Every sp i noticed changes on performance and features on web server such as WebSphere, tomcat etc..
It is frustrated to admit your own stupidity.
It is stupid not to admit it.
IBM Certified Database Administrator
Sun Certified Java Programmer
Oracle Certified Associate