What is your favorite email client/webmail and what do you like about it?

Most Popular Email Clients, Winter 2011 (from here):

I’ve been using yahoo mail for years and have just stuck with it. I like it when it works. I like using the shortcuts to compose and respond to emails (I know most systems have that). I like all of my folders, although recently I have deleted many and combined them. Their search feature is okay. I like being able to download several attachments as one zip file )(again, other systems do this now too). I sort of like the built-in chat, when it works. Their interface for smartphones really stinks, but I don’t have a smartphone, so it’s no bother.

Next Monday, we are making a transition to a new email client (well really, webmail) at work, and it’s a really big deal. We’ve been with the old email client for over 10 years and the new system is going to be very different. I need to spend some time thinking about how I am going to organize my email in the new system.