The Lula is a very good loader and I use one almost exclusively when loading 5.56 AR-15/M-16 mags. I don't have one for my Uzi, but I'm sure I'll pick one up eventually. Which is "the best loader" is relative to your specific needs and criteria. In addition to the Carmmenga, I own and use the following loaders for Uzi mags. All are good, all are different.
*The C-3 Rapid loader is absolutely the fastest Uzi magazine loader, but... The 36 round clips must be pre-loaded. Does being the fastest loader make it the best? Some think so. Given enough clips preloaded in front of the TV, this is the ultimate range loader.
*The 9mm loader for the AR-15 Beta C style drums is a very good an efficient Uzi mag loader. Only one push per five rounds and a simple two piece polymer design. Definite honorable mention if not a candadite for "the best loader".
*I've loaded thousands of rounds, (literally), using the IMI 5 round bump loader. It's all metal, one piece, with no moving parts, and is super easy to use. No question about it being "the best loader" for soldiers in the field. I think it's worth owning.
All the loaders mentioned in this thread require a short learning curve and a specific rhythm. Once mastered, all will serve you well.
There's a very nice review of magazine loaders in the Uzi Talk library.
http://www.uzitalk.com/reference/pages/magloaders.htm