For me, Mail is unusable for one simple reason. When you create a rule in Mail, it is automatically "active" all the time.
In Entourage, you can create rules, make them "inactive", then manually apply them as needed. It is a simple matter of going to Message > Apply Rule.. and voila!
This is amazingly useful because you can apply individual rules based on your own assessment of a messages content.
I have been writing to Apple for years asking them to make this small improvement to Mail. If they would do it, then I could move my emails over to Mail and everything would finally be synced with my .me account. But alas, I am destined to stay with Entourage until Apple catches up with Microsoft.
I also like Excel, as there's a fantastic add on called Expander.
