.net vs java ,which is your choose ?

In the develope world ,we have two big platform :java and .net(microsoft technique),but what is your best choose ?

I think the design task/customer's requirement is a big ractor.

if the customer's requirement is very complex ,so we should choose microsoft technique ,because ms technique is very quickly and simple do deel with all off the thing ;

if the customer's requirement is very simple ,and cusomer pay more attention to web /application response speed and performence ,then wo can choose Java ,we can deploy the Java program in diffirent platform ,just as Unix ,Linux,Windows and others ,it's crossplatform.