The article's purpose determines the criteria for high quality. It's impossible to list criteria in a comprehensive manner that would work across the spectrum. There are a few general guidelines though.
(1) Be concise.
Your articles are read for entertainment or educational purposes. It's difficult to entertain when rambling or to inform with words without substance. This rule should be occassionally broken, though. Your reader might have emotional ties to the subject so dissent could hit them forcefully. Think of dissentful points like punches in the boxing ring: sometimes it helps to slow the pace. Be wordy when necessary, otherwise be concise.
(2) Be grammatically correct.
The purpose of rule (1) is to compact your information but compactness is not the primary goal. The length of your article doesn't matter if there are grammatical errors. Grammatical errors make you stop and reread the sentence, which should be considered as a form of redundancy that should be eliminated.
(3) Use the shortest word that covers your meaning.
If the same meaning can be expressed with a long word and a short word, use the short one. When choosing between a long word and a short one, always be careful to not confuse their meaning. Do not use may when you mean might. Can is about capability; may, permissibility; and might, probability. Again, use the shortest words that cover your meaning.
(4) Be cautious of arbitrary rules.
The number of sentences per paragraph should be determined by the subject. When I skim an article to determine if it's really worth my time to read, or to refresh my memory, I tend to look at the first and last sentence of each paragraph to get the gist of the article. Arbitrary paragraph breaks make skimming more difficult. Use as many sentences per paragraph as necessary to introduce the subject, make relevant points, and to present a conclusion.
Also, be cautious of arbitrary rules about the length of a sentence. The most important thing about sentences is not their length but their complexity. Arbitrary sentence breaks to make all of them short leads to monotony. Long sentences allow information to rapidly flow into the reader's mind. Short sentences pop. Like firecrackers, a pop alone will startle and awe but a predictable series of them are bland and monotonous. If a sentence is complex and difficult to understand, or is wordy, then you should rewrite but do not concern yourself with the length of the sentence if it covers a single point and is easy to understand.