If you are still using a CRT then anything, even the cheapest modern set will be a massive upgrade. All will come with a 'freeview' capability. Some will be 'smart'.
Things I look for are;
Some are 'smarter' than others. I got a 'dumb' so called 'smart' TV about five years ago expecting it to have connectivity to anything online once the network cable was plugged into it. Wrong, there was a limited choice of what could be seen online. Make sure it has the capability to connect to what you use i.e netflix.
Other than that, even the most basic will be a huge upgrade from what you have now, don't overspend.