I find my heels lifting when squatting so I was thinking about using squat wedges.
At the moment I use plates to support my heels but I would like something more stable.
But I am not sure what angle I should choose though.
Does anyone have experience with them? If so, which one do you use (what material/angle) and how do you like them?
PS: I'm working on my ankle flexibility by doing both dynamic and static stretches but any advice on that is welcome too!
Lifting your heels when squatting indicates that you're not squatting correctly. If your heels are lifting up it's because you're leaning too far forward with the bar as you go down and up, instead of having the bar go straight up and down with no front-back movement. The weight you're using may be too heavy, or you may not be paying close enough attention to the path of the bar on the way down and up. Wedges aren't going to prevent you from leaning forward and your heels lifting.
(Not saying there's no reason for wedges--there are! Same with lifters! But they're not a solution to the problem you're experiencing. I don't use them, but a quick Google search does say that ankle flexibility is one of the reasons, so sure--use them for that! But it would be good to also fix your form in tandem with using wedges.)