The article doesn't choose one DB alternative over the other, but mentions PostgreSQL as being a stronger option in a few areas.
Selena is also quoted several times, one of which is in talking about what makes Heroku Postgres attractive.
http://blog.smartbear.com/open-source/5-reasons-its-time-to-ditch-mysql/
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Kris Pennella 2ndQuadrant US kris(at)2ndQuadrant(dot)com
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