DoTerra and Young Living are multi-level marketing companies. They are very expensive and have some unsavory back stories. Do your homework. Be careful with any brand that boasts how pure and safe they are for internal consumption. Essential oils are very strong and many should never be taken internally, but you won't hear that from anyone selling those 2 brands,
Personally, I tend to use Aura Cacia and Now brand because they're cheap and I can just pick them up at Whole Foods rather than order online. Mountain Rose Herb is a good online source, but I've heard shipping is really slow. Native American Nutritionals is also supposed to be ok.
Please do your homework and find the brand that works for you. I just hate to hear that people have spent 4 times the cost for DoTerra or Young Living because they bought into the hype. Those brands aren't even organic!!