I think the most popular option out there is the KOSO LED Headlight. It is relatively cheap (compared to JW Speaker), ECE approved (which is a huge criteria for us germans, don't know if UK folks mind), and it comes with a decent looking housing.
It really depends on what are the characteristics you want out of an option to the stock one. I wasn't concerned about the actual level of brightness but I wanted a headlight that looked like the old XS650 so I bought a sub $100 light from Dime City Cycles. If you want a very high output LED unit then there are plenty of options both in style and amount of light they throw out.