New (to me) options - Fiio JM21, Shanling M6 Pro (used), Hiby R4, Ibasso DX180 (used)

I've been looking around for my next DAP and these 4 all seem like a solid option.

I found an M6 Pro and a DX180 available used ($225 and $390, respectively). Geekwill says they have the JM21 in stock at $200, and the R4 EVA edition is still available directly from Hiby @ $320.

I want balanced output. I carry about 800GB of music on my device and would really like whatever player I use (currently UAPP) to manage all of it. I only use IEM's for listening (currently TRUTHEAR Crinnacle RED:Zero).
I only stream Plexamp (so don't care about the other streaming services) and I use a scrobbler.

Can I get some feedback/help on deciding between the options?