Honestly, I've cycled through so many manga sites chasing that 'new chapter' rush. Speed is everything when a cliffhanger is fresh. My mainstay has been MangaDex for ages—updates from scanlation groups pop up there almost the second they're done, especially for bigger series. The community uploads are lightning fast. That said, if you're following something ultra-popular like 'One Piece,' the aggregate sites that scrape all the group releases, like MangaSee, can sometimes have it up a few minutes sooner because they're purely chasing the link. It's a weird little race.
But speed isn't the only thing, right? I got burned once waiting on a site that uploaded a corrupted file super fast. Had to wait another hour for a clean version elsewhere. The fastest update sometimes means a raw, unproofed mess. I'll trade five minutes for a decent translation and proper image quality any day. Lately, I've noticed the official apps—Shonen Jump, Manga Plus—are shockingly punctual. They drop the official translation at a set global time, so there's no more frantic F5 refreshing. It's weirdly relaxing, even if you gotta pay for the backlog.
In the end, it's a scattergun approach. I have tabs for three different sites open on release day. One of them always wins.