Closed back planars are pretty uncommon these days. It seems like Audeze is really doing the most work in that market. I have only heard their open backs but I know lots of people like the Sine (on-ear) if you are ok with the comfort. I’ve heard good things about the EL-8 but there were some silent revisions that you have to be aware of. And then there’s the iSine series which sort of fills the same use cases, but of course those are IEM planars that are in-ear.
If you aren’t in a rush, I would suggest waiting to see how the Audeze Mobius shapes up. I believe they are shooting to get the campaign pre-orders out in the next month so there will be plenty of reviews that will follow shortly. I am in the pre-order myself. In fact, the main reason I joined was the fact that it is a closed back planar with wireless bluetooth capabilities, not even mentioning all the additional optional DSP features. So even without all the gaming/surround sound stuff, it could still be a good, general purpose portable headphone.