I personally like Solas for Mage support/cc because of his specialization (w/ Pull of the Abyss, Restorative Veil) and can leave him on auto pilot for the most part. I also like Winter Stillness and Flashpoint to have synergy with Restorative Veil to spam spells. The AI is just bad using Vivienne's Knight Enchanter spec, but speccing her for support can work too.
Varric for Archer DPS is good. Sera is very good too. I always like a rogue archer in my party for ranged DPS and lock picking. Taking both works too depending on your Inquisitor.
Blackwall as the Tank with Champion is un-killable. 'Nuff said.
I like Cassandra as a two hand DPS, especially for closing Rifts. Using the popular Wrath of Heaven/Spell Purge combo wrecks enemy parties.
You seem to value a balanced party, which is good. However, there's really no right or wrong answer. How you utilize your party is more important in my opinion.