Sock tans

I'm a fan of taking my recovery runs slow to help get the most out of them and hopefully ensure that I'm actually recovering. It isn't as important right now in June, but its good to be in the habit for later in the season when recovery is vital. So I would do heart rate because the difficulty of hitting a certain pace can change drastically depending on the days and circumstances leading up to it.

When I first got a watch with a heart rate monitor I remember obsessing over the heart rate vs pacing, but it's not essential, rather just an indicator. On a cool fall morning it might be accurate, but when you have things like heat, humidity, and even elevation to a smaller degree affecting the heart rate it can add up in bpm even if it doesn't effortwise. I've always viewed zone 2 as the ideal easy run, but with other things I mentioned before affecting you zone 3 can be easy too. high zone 3 or above is probably too much for easy paces imo, unless the heat is brutual or you're coming off an absolute monster workout and the heart rate probably won't get much lower anyway. But in fairness, I have a low-30s resting heart rate, so maybe for someone with a higher RHR the same amount of effort for me means a bit higher heart rate for them.

I'd personally do a little bit of training how you normally do so you can get some good data on what effort coorelates to heart rate and zones for you before you base training off of it.