What David says.
In addition, you might want to check the
Performance Whitepaper, which describes a few scenarios that have been tested under load. Also, for more help you might want to get in contact with either Liferay's office in your region or with a partner - as David suggested. Liferay's staff will be able to point out partners with expertise either in your technology stack, industry or load requirements.
To be complete: Without having hard numbers, probably Tomcat/MySql are the most common deployment platforms. However, that doesn't imply that the other ones are not supported - it's just the choice of the easiest infrastructure to set up, or what people have experience with.
My typical recommendation is to choose the environment that you (your team) can maintain best. There's no use in running on an appserver that somebody recommends if you can't recover it when the underlying server fails (disaster recovery)
