Lots of people here recommend Octopus Agile, for example. I have the EDF EV tariff that I'm very happy with, and doesn't require a smart meter which suits me better.
The Octopus tariffs are very popular on the forum that's for sure.
I have just joined the EDF "Go Electric" tariff and moved from a EDF Eco 7 tariff with them.
@Harry_Zoe is correct, you can still apply to go onto this tariff and IF your meter is not suitable for an upgrade, they will still allow you to join and retain your old meter, but will put you on a constant flat rate tariff of 12.12p / Kw.
But, future switching is going to be harder if you don't have a Smart Smets 2 meter installed.
Given this, I strongly suggest asking your present supplier to install a new meter before your contract expires.
Switching to another provider is SO much easier then.
I have just had my old Eco 7 meter replaced and up and running on my "Go" tariff in less than 2 weeks !.
This allows "Off Peak" rate at 8p / Kw from 9.00pm - 7.00am Monday to Friday.
And the same low rate ALL WEEKEND.
Some members who have switched to Octopus and then found out they require a meter replacement to gain access to the cheaper tariff's, have been waiting a long time to get the work done, then another wait to get onto the EV friendly tariff !.
Switch before you ditch is my advise or you could be in for a LONG wait to access the cheaper rates that DO require a Smart Smets 2 meter installed.