Desktop client.

Being productive in Gmail feels impossible. Even in comparison to the decade old outlook 2007 I feel like I'm in less control.

The interface feels slow. The gui controls are limited, opaque and have all the GUI concessions that only webapps have to have. I don't know if users would ever accept this from a native desktop application, and it's a damn shame that they've still managed enough market-share to kill Thunderbird and turn that into a directionless turd. I don't how I'd ever mange my professional email workload in gmail.

With their interface, emails are something that happen to you and unless you get to click "archive" and never think about 99.9% of then again, it's impossible to keep up.