i have 1440 shure , meze neo , aonic 50 , i have no more stax 404 , sony 7xxx, i become old , 40 year of headphone , i haven't good hears anymore
budget planar : you dont have a lot , i have see stax edfier for 230 ..
Here are the links to the reviews made by Amir
HE400SE review: https://www.audiosciencereview.com/forum/index.php?threads/hifiman-he400se-review-headphone.28771/
Sundara (open) review: https://www.audiosciencereview.com/forum/index.php?threads/hifiman-sundara-review-headphone.22529/
Maybe this helps you.
The Hifiman store has refurbished headphones too, to a reduced price.
I have a HE6SE and a Sundara (open) and I like both very much, but I cannot say anything about the other Hifiman models.
Most open headphone are a bit weak in the lower frequencies. A bit of EQ helps. I eq all my headphones, all headphones' sound can be improved.