Where can I find decent/high quality scans/translations of popular manga like Jojo or One Piece?
I'm especially looking for a good quality translation of Jojo Part 5. I've been using mangapanda which is complete ass. I'd prefer to view them online but I can download if necessary.
Try downloading entire volumes from sites such as madokami and then use a specialised manga reader for the comfiest experience. I myself use mcomix on my Linux box.
The quality of the images should be the best there is since you'll be downloading uncompressed files released directly by the scanlators