Ask HN: What is the best Gmail client alternative?

Gmail.com totally sucks now since they've pushed the new UI to everyone (no revert back option). We all hate it, it's confusing, can't even find out if I have a new email because of the color/font/bold they use. Especially when you use Labels. And yeah, it's simply ugly and slow. Hurts my eyes and brain every time I look at my emails...

What is the fastest/lightest client out there you guys use to handle your @gmail.com stuff?

Thanks!