I joined Bulb around 4 months ago after my previous provider, Bristol Energy, substantially increased the electricity prices. Bulb sources 100% renewable electricity and seems to be one of the cheapest in the market. Since I joined, they have slightly lowered the cost per kWh, which is something that I had never experienced with previous utility providers. Their online portal shows your electricity consumption in graph format, which is great to monitor trends (obviously only relevant if you submit regular meter readings). There is also a phone app that works well.
Customer service so far has been very good, although I am conscious that I haven't asked Bulb to deal with any complicated issues, like faulty meters, etc.
So really happy with the switch and glad I am supporting a smaller company focused on renewable energy. And they are still offering a discount code for new joiners, so you'll get £50 credit on your account if you join Bulb with this code: www.bulb.me/saraandcarment6622