I have multiple adapters for retro controllers and all seem to function equally well. I originally started out with these NES to GC adapters (
http://www.retrousb.com/index.php?cPath=22&osCsid=d1114f52f4dc7b79937877e5fd14a6c9) which work great, but I eventually grew tired of the hassle of being tethered to the console.
I then purchased this dual system adapter from Mayflash that works with both SNES and NES controllers:
http://www.amazon.com/gp/product/B0..._m=ATVPDKIKX0DER&pf_rd_r=043A28HYH0NTPDYWEAQA. It connects to the Wiimote and works perfectly fine. The one issue is that it adds some bulk. I've used it with NES, SNES, and Super Famicon controllers, the latter of which is a better choice due to the shorter cabling. Still, I wish the entire connection was a bit smaller. All in all, it's cheap and gets the job done.
Then I got the WiiU pro controller and that has pretty much become my default controller for emulation on my Mac, iPad, and now Wii. I also use it on my Xbox 360 through a CronusMax adapter. The great thing about this is that it's comfortable to hold, wireless, and a single charge provides upwards to 80 hours of gameplay. And as I mentioned, it's compatible with most everything I own.
There are also two future devices that you may be interested in keeping an eye on, as both are expected to hit the market soon. One is the blissboxadapter, which promises to allow simultaneous connection of four classic controller inputs over a single usb connection. The developer says Wii support will be added next year. (
https://twitter.com/BlissBoxAdapter)
The other device is the Kade mini console, which allows for both input from classic controllers and output to a number of classic systems. This is being touted as the ultimate all-in-one controller solution. (
http://kadevice.com/)
If in the end, you do decide to go with the raphnet adapters, here is the response I got from him regarding lag. This was for the SNES adapters, but I imagine all of his conform to the same quality standards. I like that his adapters don't have bulky connections and have come close to ordering one for myself before finding out about the devices above:
"The adapter itself does not add much lag. The worst case is 2.84ms. Details here:
http://www.raphnet.net/electronique/extenmote/index_en.php#7
I also have an SNES controller to Gamecube port adapter, but due to the way the firmware was coded the latency is fixed at one frame. (approx 16ms)
http://www.raphnet-tech.com/products/snes_to_wii/index.php
Both adapter are absolutely usable in my opinion, but the Wiimote version has a lower latency."
