The only Madrid-London route which Ryanair and easyJet both fly is Barajas-Gatwick. Ryanair also flies Barajas-Stansted and easyJet Barajas-Luton.

I have flown from London to Madrid on both carriers and would choose Ryanair even if both carriers' fares were the same.

Ryanair punctuality for me has been better (although my last two flights on easyJet were on time). I prefer the Spanish-based Ryanair cabin crew (not all of whom are Spanish, by the way) to those of easyJet. But perhaps more importantly, boarding a Ryanair flight is generally more pleasant, especially at airports which have clearly marked lines for "Priority" and "Non-Priority". In comparison, boarding an easyJet flight can be a truly ghastly experience particularly when one has to fight through the "group B" passengers to board.

So, no, there is no good reason to pay more to fly easyJet (in my opinion).