I would say that yes, the EPQ is a valuable qualification. If you get an A or above in it, you can get reduced offers from good unis, such as Birmingham, Leeds etc, just to name a few Russell groups. This is good because it allows you to put a Russell group as your insurance choice, as a typical AAA offer would be lowered to AAB or even ABB in some circumstances. It also just makes life easier for you if you want to firm one of these.
Additionally, EPQ teaches you skills valuable of a university student, such as independent research and referencing. This will show and you can talk about it in your personal statement.
They are also good for Oxbridge! Even though they don't lower your offer, they give you a chance to research a field/topic related to your course and get great expertise which is amazing for interview, personal statements and sometimes you can submit parts of your EPQ as some of the written work some Oxbridge courses require.
Last but not least, if you find yourself in clearing or failing to meet your university offer by a grade, that extra qualification may make the difference between getting a place at a new uni, or leading the university who's requirements you failed to meet to reconsider you if you missed your offer by a grade.
I personally really enjoyed doing my EPQ, yes it was a lot of work but in the long run it'll pay off.