In each game there are always one or two characters that standout as The Best for me:
Origins:
1) Allister (A Bioware main male companion who isn't dull! Suck it Carth, Kaidan, Jacob and Vega!)
2) Shale (Award for most different companion)
3) Sten (An intresting, different philophy who likes and dislikes you based on standing up to him rather than agreeing)
4) Morrigan (Intresting way of speaking and voiced by Claudia Motherfucking Black)
5) Zevran (Shameless assassin *******).
Bonus demerit for Oghren for not doing or saying anything intresting outside of Orzamar.
DA2:
1) Varric (Fun, funny, feels like a real friend and person and has epic chest hair).
2) Merrill (Cute, good voice actor and I really like her act of her one-elf determination to save her people's history. If she ever learns what we learn in DA3 she'll probably kill herself).
3) Anders (For being the Bioware companion who most takes their future and the story into their own hands rather than being passive and for going on a character arc and journey. I think executing him is the right thing to do but it is because of the goodness of the arc that I feel that way as opposed to my usual "Save the companion no matter what")
4) Carver (The fact he is a jealpous arguing ******* causes conflict with Hawke which is way more intresting than Bethany's whining. Also doesn't force me to be a not-mage)
5) Fenris (Just makes the list. Very cool but his anti-mage psychosis is too hard to swallow at some points)
Demerits for Isabela (Stupidly oversexed in apperance and dialogue, comes off as very juvanile) and Bethany (God you're dull).
Tallis would be in my top five if she was around longer.
Dragon Age Inquisition:
1) Cole (For being very different, very intresting and backing all that up with excellent in game dialogue. Also he saved me from the Envy demon).
2) Cassandra (For being honest in her beliefs without being a fanatic and for being willing to change what no longer works. Also for beign the put upon straight man to everyone else's wise cracks and for being a warrior woman who looks the part).
3) Solas (For being really intresting and almost never a dick about Spirits or Elves. Bioware companions have a tendancy to get really butthurt if you disgree with them Fenris being the worst example).
4) Dorian (For beign a facinating insight into the Imperium, cool, sassy and daring to break with his people's more evil traditions without abandoning them).
5) Iron Bull (For being a Qun practisioner without being a liche).
Sera I don't like but I see what they were trying to do so I don't regard her as bad character, i just don't feel it worked.
Vivienne however just comes off as a ignorant, stuck up ponce with nothing to recommend her and little intresting to say. I don't even like her character design.