Much as I like my long focal length eyepieces I agree with Steffen and Tony, I wouldn't buy a really spiffy low power eyepiece first (for years I used a TV 32mm plossl). I have a 10" f/5 Dob and for deep sky objects I use my Pentax XW 10mm more than any other eyepiece. For planets I'll most commonly use a Pentax XF 8.5mm or Pentax XL 7mm eyepiece. I'd choose something around these focal lengths (~7-10mm) first. I am happy to cherry pick eyepieces from different series and manufacturers, e.g., my collection includes one T4 Nagler, a pair of Denkmeier 21mm oculars and some Radians (the Denks and Radians are mostly used in a binoviewer). Can you tell from my choices that I like lots of eye relief?
I see from your profile that you are a member of the Northern Sydney Atronomical Society. Can you attend some of their observing nights and try out some eyepieces belonging to others? Alternatively, perhaps buy your first spiffy eyepiece of any series secondhand so if you don't like it you can resell it for a relatively small loss. This is what I did when I was interested in the Pentax XL and TV Radian series several years ago but couldn't find any local users of these eyepieces at the time.
Best of luck with whatever you purchase!