I personally prefer an IMI UZI.
I was at the 2005 UZITalk shoot when Vector was there:
https://www.uzitalk.com/reference/pages/UTshoot2005.htm
Rex of Vector handed out some information with tips. I recall one was about fitting topcovers and how the Group receivers were not to IMI spec. He had hand drawn pictures of the top of the receiver showing the difference between a Group receiver and IMI. Not a big deal but something that may be something to look out for when fitting.
He also said that when the receivers come out of heat treat the bend in a "banana" shape. They would put them in fixture to straigten them out after heat treat. I have seen several Vectors that were clearly not straight.
I have a friend that a full auto Mini that wasn't straight and was never reliable. He sent it back to Vector at least 3x. On it's last trip back, it got ran over by a UPS truck. I wish I still had that picture he sent me. It was destroyed.
Ralph (president of Vector) felt bad for him and he traded out his personal Mini (since they didn't have any left) for my friend's Mini. That one runs well, I would assume so since it was hand picked by the owner.
All that said, I see a bunch of Vectors that run well too. I have seen some that run well and then the trunion weld breaks and then you need someone to re-weld it. I have heard of the welds breaking on an IMI as well but that is a lot more rare than a Vector.
Again, the bigger issue to me is a bent receiver something I don't want to have to deal with. I have never heard of this issue with an IMI unless it was run over by a truck or something.
Best case is you buy from someone you know that you know it runs. However, me personally, I would have more piece of mine if it were IMI over a Vector.
I remember when the Vector's were coming out. IMI UZI's were going for around 3K back then. The Vector's were introduced I think for around 2500 depending on quantity. This helped to slow down the increase in price on IMI UZI's. I was happy to see this is as it gave me more time to afford to get another IMI UZI.