Zen suits me. If you join them, then you have to provide your own router anyway. However get the latest version of a router from your manufacturer of choice to get the best performance; this may well cost you over £200..
Zen's monthly cost for 80/20 business class unlimited service with line rental is a tad over £52 on a 12 month contract. So if you are looking for something that is cheap and cheerful then Zen is not for you.