I don't think it's better, Esteban, I'm just more familiar with using it. One of these days I'll spend some time coming up to speed on WKO+, which is clearly more comprehensive from a capabilities standpoint. Right now, what I do is just easier, for me, on the website. Plus, I like being able to see my data anywhere I'm on the web. Then there is a smart phone app for the web service that lets me look at a planned workout on the go. It's worth noting I also link the web service to my iPhone calendar, so I can see the workouts there, alongside my other commitments. That helps me plan my day; deciding whether to to do the workout as part of my commute, before work, or after work.
Do you upload using the Device Agent applet? Are your versions of everything up-to-date? I haven't had an upload issue in a long time; definitely not since I went to the Mac.