Depends on where you live!
Gigaclear and other alt ISP's might be in your area, just that if you simply use the mainstream broadband availability checking websites, you would never know they exist.
Live in a recently built (last 10 years) house, FTTP might be an option.
Otherwise your choice of ISP really is down to what other services you need: Static IP address, IPv6, uplink speed, VPN supported, no traffic shaping or management etc.
I've found EE to be reasonable (apart from the few well publicised service outages when the Three mobile broadband has kicked in) and have when necessary been able to talk directly to the network engineers. Obviously now EE is part of BT, this situation needs to be monitored.
NB. I assume you currently have a home broadband connection, so the business can expense the upgrade to a business service (or check your employement T&C's as if home working is expected/permitted you will be able to expense some of the home costs).