I've finally found my controller! Way back when I started this thread I was suffering from poorly made replacement sticks and a couple poorly described "like new" controllers I ordered from ebay, and I had resigned to using whatever controller was available.
Recently I ordered a Gamecube to N64 adapter from
http://www.raphnet-tech.com/products/gc_to_n64_adapter/index.php and I feel I've finally arrived at my perfect solution.
This adapter is great for a few reasons:
Gamecube controllers are cheap and easy to replace should they wear out
I cannot find any input lag difference from the standard N64 controller
the joystick sensitivity is perfectly symmetrical
tilt range and deadzone feel great
reprogrammable buttons make it easy to find your most comfortable button layout
ability to save multiple controller profiles in case you ever find a reason to play something other than smash
the length of a gamecube controller cable is certainly a plus as well, I can sit wherever I want!
For me, the only drawbacks of using a gamecube controller are the L and R buttons. It does take some getting used to, but I have little trouble getting my z cancels now that I have adjusted my muscle memory. ( I find that setting the L and R buttons to be Z and R respectively, and then programming them to register a press at the 50% threshold instead of the fully depressed 'click' makes things very comfortable.)
The adapter is around $30 shipped to the US (keep in mind the price on the site is Canadian currency). I figure this could be a great option for many people who already have a gamecube controller, and even if you have to get a controller plus the adapter, it is probably cheaper than any Hori controller you could find. I have also seen a Hori controller wear out and have deadzone problems, which makes the gamecube adapter a safer option.
If you are a super serious player you might want spend the money and play with Hori controllers because the Z and R buttons are definitely preferable, but for $30 this adapter satisfies all of my needs and has breathed a new life into my smash game. I didn't improve much just from getting this controller, but at least I can't john about messy N64 sticks anymore.
I didn't mean for this to be so long so I apologize, and I want to say that I am in no way affiliated with raphnet-tech. I only hope that this can make the game more fun for some of you struggling to find a good controller.