I've had a look at one EDF deal, and it mentions that you agree to a smart meter installation. Are smart meters still specific to individual companies, creating problems if you want to switch again in a yr or two?
If the smart meter is SMETS2 compliant then it should be transferrable between suppliers. If it was one of the earlier SMETS1 standard then it may need replacing when you change supplier, but that's at their cost... and your disruption.
There's been a raft of small suppliers go bust over the last 6 months, but Ofgem has in place a Supplier Of Last Resort process so the worst that should happen is you end up with a different supplier on their standard variable tariff and any credit balances should be protected.
The market is dynamic, so whoever is competitive today might not be in a couple of months. Unless cost is the key concern, I'd choose a supplier that has good customer service and charges a fair price. Also, features like a decent mobile app for submitting meter reads and viewing bills etc. are worth considering, although should be a moot point if the smart meter is doing its job properly!