For everyone looking to get max affection for all the pub companions for the legacy title "Republic Squad Leader", I use the following site to see what gift each companion likes the best. I also don't start the conversations until they are at least at 8000 affection, because that is when they are at rank 5 for affection. I buy the green rank 1 gifts for 0-4000 affection (about 60) and rank 2 gifts for 4000-6000 affection (about 40). Then I just buy whatever is on the gtn, which will usually be the rank 5 gifts.
*Also Qyzen is a bitch to level since he has no favorite gift.
**Elara, Kira, Doc, and Risha are also difficult to level unless you are romancing them.
Companion Gifts
Affection Guide