Gyazo nailed the instant-capture experience: grab a region, and a link to the image is on your clipboard a second later. It is fast and frictionless, which is exactly why people love it. The same model powers Zight (formerly CloudApp), Droplr and similar tools.
The trade-off is custody and cost. With Gyazo, your captures live on Gyazo's servers, and the genuinely useful parts - history, search, longer retention - sit behind a subscription. FTPie offers the same one-second capture-to-link flow, but the link points at a cloud account you own, for a one-time price.