Not an easy thing to do and one has to think of the priorities.
The only cRPG i've ever played that come close to DnD in both rule set and interface is probably ToEE. It had both the setting, the rule set and the mechanics of a core PnP game. However is it my favorite iteration of a DnD game? Surely not. Even though i play turn based games and love some of them (Jagged Alliance 1 and 2, the X-Com series), this particular version of DnD, though adequate and enjoyable, fell short of other contemporaries.
Baldur's Gate in example, with its simultaneous turn execution (pause and play) was for me far more entertaining and an overall better computer game then ToEE. Even beyond that, IWD though smaller and weaker in the grand story line and character interactions, was setting, artwork and atmosphere wise better then BG. Especially the fact that you created your entire party (yes i know you could do this in BG as well by starting a MP game, but it just "felt wrong" doing it).
NWN on the other hand, did extremely well in its modular design, which allowed for many user custom based adventures/modules.
So how to proceed in making the best "faithful" version of DnD? I'd say depends on what you want to achieve with it. If it was purely up to me, i'd either go the BG way or the X-Com/JA2 way. Depending on the "elegance" of the execution. But either way, i would try to stay as true to the basic rule set as possible. I actually adored the high lethality of the BG1 and i think it represented 2E fairly well.