Thinking of Switching From British Gas

BG have been a nightmare for me. I have a faulty smart meter (1st gen) that doesn't work properly. It freezes etc and they've even told me it isn't working, but they refuse to put in a new one and told me to go on direct debit instead, which I don't trust due to horror stories about BG - and the customer service are rude and unhelpful. So I've read a lot of reviews about Octopus and have decided to switch today. Could anyone give me advice on what's best please? Fixed Tariff (DD) or Tracker Smart Tariff? I need one that'll save the most money as I work from home and have children and a bearded dragon (he doesn't use a lot but still his bulbs are on all day), so we are using electricity and gas all day, every day. I have a 2-bed house, so nothing too big. I've only topped up a smart meter since moving out of my parents years ago so I'm new to all the technical stuff and I don't want any surprise bills that I can't afford, that's why I've been reluctant to pay DD as with the smart meters, I kind of know how much I use every week and notice if it goes up or down over a period of time. Thank you