Current leveling "strat" is:
- Start on Master
- Take the weapon off one of your followers(whichever you can equip), they're better than the shit you start with. Also take a follower if you're solo but that's obvious.
- Check bounties for Kulle or one of the non randomized cursed chest bounties that's near the teleport(example the cursed outpost). Can reset the game for Kulle, it's 1/3. Maghda is good too apparently? Seems kinda far but eh.
- Doing that early bounty will give you level 4-5 and a full chest of rares, which speeds up the early leveling process a good bit, as long as your luck isn't shit on rolling Kulle. You can just check and if it's not there, skip to next step.
- Drop difficulty to hard, go to Halls of Agony, clear until you reach a dead end, recall, reset the game and do it again. Should do that until 12 or 20ish, whichever you prefer.
- Do Rifts until 70 once you're done with Halls
- At 12(and possibly 8 if you happen to be in town), go to town and check vendor for rings+amulet with +dmg rolls, reset a few times, ignore act1 as the vendor is too far imo. If you're not getting lucky, just forget it. Note that only one vendor per town sells accessories, so don't bother checking the others.
- At 20, if you want, do Leoric on story mode for the crown. It's good to cube eventually for many classes especially in early gearing process, and it's nice for leveling(comes with a socket always, and doubles ruby xp), but it takes a while to do if you don't have a movement speed skill on your class, so up to you wether or not you do that
- Optional but you can do a set of bounties at 23(turn in, you can start a bit earlier) and hope you get Cain or Born plans from them most of the time(I wanna say all the time but not 100% sure), which is pretty nice to level a bit faster, although it's debatable wether or not it's worth it.
- At 45 you can try crafting a lvl 60 weapons with -req, there's no 2H melee weapons anymore at 60 though so you'll have to craft a 1H(or if you're a DH you can make a bow). I wouldn't spend too many mats doing that, 45-60 still goes pretty fast. If you do get one, bump difficulty to torment 1 or whatever still feels fast(should be around master or T1, can be T2 depending on the rest of your gear/class)
- At 61, after you find your first death breath from an elite, use it to upgrade the blacksmith and spam lvl 70 weapons. You want one with level req as that'll let you basically torment 1 until 70, which is a ton faster. Can also use the enchanter to reroll mods but you might need more DBs to unlock weapon enchants I'm not sure. If you do reroll, it's easier to roll lvl req if the other secondary mod is a CC mod(chance to fear/slow/stun/blind etc).
In group it takes like 2ish hours now and solo about 3hours. If you don't optimize and shit it might take a bit longer, but it's still pretty short nowadays, large change is the new console kill streak xp bonus shit that helps a ton, especially solo.
There's a good google doc with a ton of useful info(including the leveling shit I just said, although with some differences):
Diablo 3: Ultimate Guide for Patch 2.4 - Season 5 (featuring; New Builds LVL 1-70 Guides)