Having owned an IMI uzi, mini uzi, micro uzi, MP5, MP5k and the rest of the HK91 family. I can tell you that the uzi is what I would rather go to war with. Love my MP5, but the uzi has a better trigger, can be carried loaded with without the safety on thanks to its grip safety, and is stupid simple to operate and breakdown. The uzi is less complicated and more reliable IMHO then an AK, and probably easier to build.
I found the grip safety to be annoying so I pinned it. I also do not like the ratcheting mechanisim which I've also removed.
The real beauty is that barrels are cheap and with an open bolt without a magazine inserted there's no mistaking it for being loaded.
Great trigger however I've shot an MP5SD and on the first burst hit a clay pidgeon at 78 yards!.
I cannot even approach that with an UZI. Then again my UZI did not come with an MP5 Price tag!