The most common one for me to use is Fade Touched Obsidian (on hit gain 3 guard), mainly because I can easily farm it from the chest behind a locked door in Redcliffe. I would just swing by Redcliffe on my way to any other area in the world.
Other than that, it would just largely depend on what I happened to pick up since I didn't like to run around simply trying to farm mats. That said, the Hidden Blades mats were probably my favorite overall, especially on dagger rogue, stacking several different levels (Plush Fustian Velvet, Ring Velvet), and I spent some time trying to get the PFV before crafting my last dagger in that game.
When I did my archer run, I was getting tired of crafting and just threw on whatever I had. I know one of my bows had the chance for walking bomb, and was a pseudo Punched By The Maker.
Heal on Hit (Snofleur) is pretty good for ranged party members. Or the damage bonuses for not getting hit (Vargesht Scales, etc). Damage bonus for multiple enemies (Bloodstone), Horn of Valor (Snofleur) are pretty decent on melee.