Origins is definitely the best and the closest to that classic Bioware feel you like.
DA2 was polarizing but I enjoyed it. Very different from the first mechanically. Worth playing tho, IMHO.
DA:I was... not fun for me. I feel like they tried to modernize the formula and added all the worst parts of modern (at the time) games, namely HUGE time sinks for no reason because it's not a fucking MMORPG that makes money by the hour. /deep breath Sorry, I am still a little bitter at how that game turned out. Anyways, probably worth checking out, maybe you will feel differently. But it wasn't for me.