Which Camera is best?
Here are a couple of things to think about:
-NEX line has a larger sensor than the m4/3 cameras. This translates into much better high ISO performance - ie shooting when it is darker out will give you better results. (Also the impact that this has on effective focal length and depth of field if you care about that)
-m4/3 cameras can be found for cheaper (by a lot) used (Used EPL1 for 300$ is pretty awesome)
-NEX only has 3 lenses right now (with one more coming out soon) but the m4/3 line has a buuunch of options for native AutoFocus lenses.
-Both can use adapters to put on all sorts of manual focus lenses (The NEX just got updated for "peaking" which is AWESOME for focusing and getting depth of field with a MF lens)
So my opinion is that the NEX is a better companion for an established photographer and the m4/3 (such as the E-PLs) are better for someone looking to step up from a P&S without much knowledge of cameras.
Of course I hate saying "buy this one" so my normal advice is: Hold Them! How it feels in your hand and how easily you are able to navigate the menus and such are very important factors in making a camera something you'd WANT to use. Any of the kits you mentioned (make sure to get the 18-55 with the NEX not the 16mm prime unless you are an advanced user) will work in the end, and work wonderfully.
I should toss out that unless you are heavily invested in either Nikon or Canon right now I don't think it's worth waiting for their offerings.
Hopefully I didn't overwhelm you...I often do that when it comes to cameras :'(
Clicking the mark as good answer button helps us highlight the best answers.