I must have missed this thread before. My wife's sister in Edinburgh switched to Bulb over a year ago and thinks they are great. They do get excellent reviews on Which? We we just up visiting her last week and she said that she decided to stick with Bulb again this year.
We switched to Octopus last October, again a Which? recommendation and have been delighted with them. We are on an agile tariff so the price varies every 30 minutes depending on expected demand, many times this last year we have had negative rates so in fact they pay us to use electricity. As long as we can avoid using electricity during the high period between 4 and 7pm it is great. The last bill showed an average cost/kwH of 6.15p. Great scheme for us retired folk able to choose when to cook, clean etc. Cheapest rates are usually overnight.