Have you done any leveling since Cataclysm? Blizzard did a great job of streamlining all of the Azeroth questing zones. There's not really any need for a guide now. You get quests in approximately the same order you should complete them, and you'll level plenty fast just by going to the nearest quest location on your default world map, doing the thing your default quest tracker says to do, and then going back to the question mark on your default world map to turn it in. A guide might shave off a
tiny amount of time, but leveling is so fast now that there's not much incentive for guide authors to spend all that time, nor for potential guide buyers to spend any money on it.
My last leveling character went 1-85 in just over 5 days played, with no guides, and a lot of lollygagging and idling along the way. If you were actually paying attention most of the time and not alt-tabbing to watch TV, I'd guess somewhere around 4 1/2 days would be a reasonable goal.
The only areas that can still be slow (eg. quests poorly sequenced or too spread out) are Outlands and, to a much lesser extent, Northrend. Any old guide for Outlands should still be mostly accurate (with the exception of stuff like the Thrall questline in Nagrand, which was removed in Cataclysm since Thrall has moved on to other things) even after all these years, including the one that comes with
TourGuide, though you will probably find yourself outleveling the guide very quickly, since XP gains have gone up and XP requirements have gone down over the years. If you're at all familiar with Outlands questing, it's probably faster to go without the guide, even with the sprawl. Northrend wasn't nearly as disorganized quest-wise as Outlands, so I'm not sure how much a guide would really speed things up, even if you aren't familiar with everything there.
If you don't like having to look at your map all the time,
TomTomLite will automatically point an arrow to the nearest quest objective, or you can use
TomTom and set the objectives as waypoints yourself via the quest tracker. I prefer TomTom, because I like having more control, and I think the new arrow graphic in TomTomLite is horribly ugly, but both work just fine. It just depends on what you want.
If you need help finding quests to pick up in the first place, check out
QuestHubber or
Wholly; both will add exclamation points to your map showing you where to go to get quests.
Make sure you turn on
Automatic Quest Tracking in the Interface Options, so quests are automatically added to your tracker when you pick them up. You can left-click on a quest to open your world map with the clicked quest's location(s) highlighted.
QuestMyMap is another useful addon; it cleans up the bulky quest UI on the world map.