Hi Revan,
For deep sky start by getting the widest true fov possible and then go up magnification in steps of about 1.5. I like the 'space walk' of ultra-wide eyepieces so you would be looking at a 31mm Nagler ($$$) or 30mm Explore Scientific (less $$) or a 28mm William Optics UWAN (very rare). I have the 28mm WO, then a 20mm, 13mm and 9mm (all Naglers). Only one of these was bought new, the rest are from IIS classifieds. Alternatively you can buy quality super wide (ca70 degree afov) eps much cheaper. Start at about 35mm to get the max true fov. You don't get the full space walk but they aren't objectionable.
For lunar/planetary minimal glass rules and narrow afov is OK. I recommend Abbe orthoscopics (generally just called orthoscopics) but _good_ plossls are OK too (there are a lot of junk plossls about). I love my 7mm University Optics ortho but you can only get them second hand now. I also have the 5mm but the eye relief is a bit too short for comfort, I should have got the 6mm. BTW My UO 7mm ortho is much nicer than my old Celestron 7.5mm silver top plossl.
I was just looking at this thread (for other reasons) and you may find it useful
https://www.iceinspace.com.au/forum/...d.php?t=196781
also
https://www.iceinspace.com.au/63-652-0-0-1-0.html
cheers,
David