From what I am reading, ANY .22 upper kit for a M-16 is higher maintenance than some hot blond with big tits from South Beach. Is this an accurate summary?

I had one .22 belt fed upper that after much frustration was eventually sold for a huge loss. Although a few may get them running for a while,  they eventually will either stop working or require continual alterations.

Are there any .22 Kits that I can simply attach and go?
If not what are the top 3?

I really like the Kuehl  7.5 Upper, what is the general consensus of that particular item?

I don't know of any that will attach and go, and NEVER have any issues.

I've got two Atchisson kits made by ceiner.  Both run 100% in semi auto.  One runs about 95% of the time in auto, including some entire range trips (500+ rounds) without a problem, then will inexplicably start screwing up until it gets pulled, scrubbed and tweaked.  The other does not and never has run right on auto, and won't run right on semi auto if I leave the sear trip and debounce weight installed.

They all seem to be very ammo sensitive - find what works best, and stick with it.  I was forced on the 95% running upper to switch from remington golden bullet milk cartons to federal milk cartons (both are copper-plated round-nose 36gr hp's), and it was definitely not as happy with the federals as it was with the remmies.  It's kind of settlted down now, and seems to be eating the federal OK.  I haven't bothered taking out the other kit in years.  I'll probably find someone with a semi and sell it off, since it's no good to me at all.

Anyone with a DIAS or RR will want an Atchisson kit - be it ceiner-made, spike's-made or cmmg-made, since they're the only ones I know of that run in full auto.  The other conversions (that czech one, dpms', the old army kit and the old air force kit) don't run in auto, and are usually stuck with 10rd mags.