Need to be more specific here. The "best" is matching whatever your hub has (if it's the HH5 it's 3x3 MIMO 802.11ac, if it's the newer "Smart Hub" it's got an extra antenna, 4x4).
Assuming you mean the Smart Hub then from ocuk's range you're looking at on of these
My basket at Overclockers UK:
Total: £98.69 (includes shipping: £8.70)

That'll give you the best chance of reaching the max 2167 Mbit/s.
However you probably don't actually want that

unless you want extreme LAN performance.
So probably a good idea to mention now your broadband speed as that's probably more important.
Also a budget, and USB or PCIe?