https://docs.google.com/spreadsheets/d/1SJ3PZRbyXocsdIkq9D0Jik6BjeMQmoLdnvgHJD-tF8o/edit#gid=549941070--> an incredibly good spreadsheet, it gets update for each new season, so it really is worth a bookmark.
You either farm xp in a group or go solo and chain killstreaks. The best solo leveler is WD (check the spreadsheet videos if you want to see a WD solo level in less than 2 hours).
DH and WD got the best starter sets, Wizard will be the strongest class this season (DH and WD will be much more casual in their playstile though and they won't be weak either).
I don't play much monk, but he's probably around the WD regarding strength. Crusader got his strong hammerdin build, but it's not the starter set. Barbarian is the weakest class in season 10.
I'll start a DH tomorrow because I want to test the new imaple builds.