Harb,
I have lots and lots of eyepieces
.
Including some of the best from the Pentax range and the Televue Naglers and Panoptics. I use them in a 10"/F5 dob and an 18"/F4.5 dob.
If I could only have 4 eyepieces, cost no issue, it would be the following.
31mm T5 Nagler
17mm Nagler T4
10mm Pentax XW
7mm Pentax XW
In the shorter focal lengths ie. 7mm and 10mm, the Pentax XW's are superior to Naglers. The 30mm Pentax XW is also a very good match to the 31mm Nagler. The Nagler has a larger TFOV, the Pentax has superior contrast and light transmission and goes a little deeper on dim objects. However, at this focal length I believe the aim is to maximise the TFOV. If you want to pop faint fuzzies you should be using a higher powered eyepiece with about a 2mm exit pupil IMO.
CS-John B