IMO it's dependent on your location as network performance can vary wildly. Might be worth getting a PAYG SIM from EE and Vodafone/O2 (they share networks) to test speed, signal strength etc.
If you are on a contract I would wait until next April when the yearly inflaton price hikes are announced.
FWIW I am paying Vodafone £7 pcm after cashback for 200 GB 5G data, unlimited minutes and texts.