I did the EPQ, and found it to be a great experience. You have the chance to research absolutely anything, I chose behavioural economics, which was a topic related to the degree I was applying for at the time, which gave me something extra to talk about on my personal statement, which isn't covered on the A level specification. If i had an interview, it would have also given me something to talk about as I had conducted extensive research and was super interested in my topic. So if you do decide to do the EPQ, make sure it's within a field you're genuinely interested in, and don't mind reading articles, watching TED talks etc.
It also really helped with my transition to university as I developed essential essay writing skills, which quite a few people didn't have, such as referencing. The only disadvantage I can think of was maybe presenting, as I'm kinda shy, but even then it really helped me, as I've had to present quite a few times at university. So if you have the time, I'd totally go for it.
I got an A* on mine and would be happy to help further if I can, so feel free to message me at any point