Unfortunately an OEM controller is about as good as it gets. Especially if you intend to use it with the Wii.

Edit: to clarify, do not buy any of the cheap 3rd party controllers they are total garbage

I recommend getting a Smash Bros U/Smash Bros Ultimate edition Gamecube controller on Ebay. It's the same as an original Gamecube controller, except it has a longer cable (which is much better for modern living room setups) and it has the Smash Bros logo on it. https://www.ebay.com/itm/225532597419?epid=8032166771&hash=item3482ca54ab:g:zzMAAOSwf-JkPDeK&amdata=enc%3AAQAIAAAA8MJ3kSPdlQoRwFXheGH%2BSzXaS99WV6wLP6TIvIyt42GMxxqldWsFvcPfknSO0kzTqKdsZkTj5azOgJkYuMzwKQUT85y1Eq4aSusXgzWNSc9lHqfJwj%2BP9Y2gwE0yKZUUV5sxL7NDb92%2B48UGfe7%2Bb4APOSt5cDrG%2BGK1zvQw%2BiI%2Fz2NpZZkoLmcN%2BumNPUat1%2F5Aq3Y%2BWeBaHm3AiAxRS4hbtWkNeMFCkWtYJ1YGy4NNvoaZ9r5Iz1ovM%2F76EPr4dKin65uQwZFa2ZIn%2FA6whjQYLubCKoZthHGN27%2B8K5uhkL1%2FSE8tghJi9Y%2Bwkw%2BsVA%3D%3D%7Ctkp%3ABFBMyNK8-pti

If you've got a Bluetooth controller you like (I'm partial to the 8bitdo SN30 Pro myself) you can use a Blue Retro adapter, to wirelessly connect with minimal lag. it's open source tech, so multiple companies make these adapters. They can be found as Single port or multi port adapters.

The "new" ones released for Smash 4 and Smash Ultimate are as good as they get. They're more or less perfect replicas of the original controllers. They even use the same connector that the GameCube uses, so it'll work on your Wii.

I am gonna pass on my official wavebird controller as family heirloom. XD