I love both games. NWN1 is hands down the game I've spent the most time on by far. Between the official campaigns, community-made modules, and playing on servers, there's no other game that even comes close to it in terms of time spent playing.
Having said that, IMO, NWN2's official campaign is far better than NWN1. The MotB expansion for NWN2 is absolutely stellar, and beats out the second expansion of NWN1 (which is damned good on its own). I really enjoyed the second expansion for NWN2 as well, but I'm probably a minority on that.
Both games can be modded, and both have a ton of content and community made modules available for them (although NWN1 has a helluva lot more available).
But do yourself a favor and don't wait for NWN2 to show up here. Grab NWN1 and play it, or at least some of the modules available for it (things like Wyvern Crown of Cormyr, Darkness Over Daggerford, and some of the top rated modules from the neverwinter vault). You can't go wrong.
Once NWN2 shows up here (assuming it does), then grab it, play through it and the expansion(s), and grab some of the best modules for it from the vault as well. You seriously cannot go wrong with these games.