DoTERRA oils are pure and highly tested in house and by 3rd parties. And, they are very transparent about their testing results. Go to https://sourcetoyou.com to find test results on each batch of oil sold by doTERRA along with sourcing and other information. You can find the batch number stamped on the bottom of each bottle.

Melaleuca, the very 1st essential oils company, has their essential oils go through more tests to ensure purity than both DoTerra and Young Living.

As far as their prices, Melaleuca sells their essential oils for between 30% - 60% less than those companies.

The 'smell test' is highly subjective and not a scientific QC test.
You need a CA (certificate of analysis) to rate quality. Or you can run an IR scan or chromatographic test to assure purity.

There are no others that match quality with doTERRA, try the smell test with your oils and doTERRA and I guarantee it will confirm what I'm saying