There are other in-game guides out there such as Xcelerated, but it doesn’t even come close to what Dugi and Zygor offer. Although I’m obviously a fan of Dugi Guides, I have given a fair side by side comparison of each guide, based on facts and what is offered by each. I’ve included many screenshots to give you an idea of how each guide looks and works within the game. I will do my best to keep this as up to date as possible, with price changes, guide updates etc as I know how annoying it is reading outdated reviews.
-Global Cooldown- Almost all spells are now on the global cooldown. This has slowed gameplay down quite a bit and you won't get to use the full potential of your spells cooldowns. For example, you cast a spell that increases your damage for 15 seconds, after the global cooldown and you're able to cast again, you now only have 13.5 seconds to make use of the remaining time. There are far too many spells on the global cooldown that shouldn't be.
I tell you my experience. I'm leveling a priest that it's 60 now and since I have also done some instances (and I have full heirloom set with 20% experience gain bonuses) and been very ahead of the guide, I skipped some zones since they were grey quest for me, well it was a real mess. Missing quests because I didn't to the previous to enable the following. Going in a zone then realizing that I couldn't do that quest because I didn't do the starting quest chain, very unconmfortable. In short what I suggest you it's not to skip areas, or make really sure that you do all the quests required (at least) and check carefully the previous zone you'll going to skip to make sure that you won't have problems with struggling finding where to start the quest chain to sync with the guide section.
If you bought Legion and have no desire to go through old content, good news! The new expansion comes with a free boost to level 100 for one character. You can buy these boosts from the in-game store whenever you want, but they normally cost $60, so savor this free one. Use it for a class that you are confident you will enjoy. As a fresh level 100 character, you will be able to immediately begin the quest that takes you the Broken Isles, the new region where Legion takes place.
DoTs: Assuming that the mob is going to live for certain periods of time, it is worth it to place DoTs up. If the mob lives for at least five seconds, cast Pain. If it lives at least seven seconds, cast VT. The ideal time to cast DoTs is when it would be replacing Flay, but you can substitute Blast if the mob will live longer. Make sure to cast Bolt on cd though!