I haven't played through enough of BG1 and 2 or Kotor 1 and 2 to rate them, so I'll stick with the ones I have played.
1. Dragon Age Origins --- The gameplay is fanatstic, I love the tactical combat and the characters are nice too.
2. Mass Effect 1 (Very close to DAO) ---One of the best plots ever and great characters. Minus a few points for the combat though.
3. Neverwinter Nights --- A true classic in every sense, but the plot and characters are not up to the standards of the first two.
4. Mass Effect 2 ---The plot is all over the place, and the characters not as strong. It makes up for this with better combat and of course the Lair of the Shadow Broker DLC.
5. Jade Empire ---Fantastic game, decent story and characters but the combat is too simplistic.
6. Star Wars: The Old Republic ---Although a lot of it is a World of Warcraft rip off it still has some pretty good plots and characters to it. Unfortunately they are all a bit shallow and leave you wondering how great the stories could have been if it was not an mmo.
7. Dragon Age 2 - The characters are not very strong, and the plot is fairly weak. But unlike the games below it does not retcon or contradict its own lore which stops it from dropping any lower on the list.
8. Mass Effect 3 - The characters are pretty weak, the plot is a mess and it retcons and contradicts its own lore on numerous occasions. Also there are way too many fetch quests and they had the nerve to try to force multiplayer into the single player campaign. It is only saved by a fairly decent combat system.
9. Dragon Age: Inquisiton ---Same problems as Mass Effect 3. The characters are weak, the plot is a mess and it retcons and contradicts is own lore on numerous occasions. Again there are a lot of fetch quests and kill x amount of creatures, or collect x amount of things quests. Unlike ME3 it is not save by a decent combat system, in fact it might be the worst part of the game.
As was stated by others, it has gotten worse since EA took over.