An RPG should be measured by certain elements. The cast of characters, for example. Check. Those are pretty amazing. Customization of your character. Yeah, done well here, too. An interesting world full of mysteries and lore. Nothing beats the Forgotten Realms (except maybe Golarion). The only drags on this game are a confusing plot that didn't seem coherent and the fact it's based on 2nd edition, which is a shitty DnD incarnation.
An absolute favorite of mine when it comes to CRPG's. While admittedly it still falls to the trappings of many Bioware RPG's, here the company has made a cast of characters and a plot that's much more endearing and complex than most of their outings. The roleplaying elements don't feel as refined as, say, a TES game or even others in its genre like Neverwinter Nights or Icewind Dale, but your dialog choices feel beefy and allow you to define your PC in unique ways.
A game I often return to, but rarely finish. BG2 has a huge game world with tons of side content, but sadly loses a lot of its fun once you start doing the main quest. My favourite aspect of the BG games is the ability to explore the game world with some freedom, and the long, linear main quest sections of BG2 go directly contrary to that. On the upside, the game has a huge selection of character builds and equipment options, and the SCS mod gives BG2 one of the best enemy AIs in video gaming.
In keeping with DnD tradition, going on into the upper character levels brings on a whole mess of more exotic threats and more complicated encounters in a grander campaign that stands out more than the last one, with plenty of side business. (Though, if we're to be honest, a "tough" fight in this engine often boils down to: "Did you disable the spellcaster(s) right away? No? Then reload until you're lucky.") Also, the humble all-text beginnings of the "Bioware Romance" tradition.
Better than the first, but doesn't have much replay value I feel.