The information i've seen has shown that the weta version is bigger than the UC/noble versions, since it was from the original mold. The other two were cast off of original props i think, and suffered some shrinkage? So they are a bit shorter/smaller. Not a huge deal. But Weta is also who made all the props from the movies, hence why people tend to value their accuracy and detail a bit more. Doesn't mean they will always be better, but we wont know until all 3 versions are released. Also, weta seems to be doing theirs in fiberglass, one piece. This would make it stronger and less likely to break if you are taking it out of the house with you. I love my UC gandalf the white and saruman staffs.. but they are crap. They are poorly constructed, my gandalf the white staff was chipped and cracked to hell and back, and needs serious repair.. and sarumans has a ball that is wayyy to small and doesn't sit securely in its head. They also feel weak, since they are not a single piece. They need to be screwed together most of the time, which is a downside to me. Some like it for storage, i don't. I'd much rather have a solid item.
If you are paying anywhere near what you have quoted for UC items, you are really buying from horrible sites. UC have some of the cheapest prices around if you shop for them. Bladecenter, and many others often have good deals on them. You shouldn't be paying more than 150 tops for the gandalf staff from UC. And the weta one is 179 from them, and then shipping varies (mine was 11 for gandy's, so i lucked out, others it is like 130 if they are in australia, etc).
Obviously, there is a lot of variance there. But there are a lot of reasons some might prefer weta, and some might prefer UC or NC. I know for sure I want the radagast and gandalf from weta. And once I see the UC/NC pictures, i'll decide if I want one of those as well. I'd love one that lights up, just for the novelty.