I primarily use 4mm, 5mm, and 6mm focal lengths to get to planetary magnifications with my 100mm and 81mm scopes, and down to 8mm when using the 152mm scope. So my planetaries are centered on that range.
My "flagship" planetaries are the 6mm ZAO-II, 5mm XO, and 4mm Celestron Abbe show in the right foreground. These I bring to bear when the seeing is superb and I am trying to tease out smallest details on the planet. They always excel over others (I've had over 400 eyepieces in my observing lifetime). Interestingly you will see a plebeian vintage Celestron Abbe Ortho at the 4mm place. I had a 4mm ZAO-II but surprisingly it was not what I would class a top notch performer, no where near the class of the 6mm ZAO-II. I also had a 4mm TMB Supermono and that was the ultimate in performance IMO. However, the small 30 degree
The other thing I do, which actually gets me within a gnat's hair of the performance of the flagship planetaries, is to use a quality Barlow or Powermate on longer focal length Tak LEs or Edmund RKEs. These two lines under Barlow (the 2.5x Powermate is actually preferred) are just amazing performers and keep pace well with the flagship EPs. So I end up using them most now actually. The Edmund RKEs are pictured in the left foreground, and the Tak LEs are in the background with the TV Barlow and Powermate. Since I wanted a 15mm so I could get to 6mm with the Powermate, I supplemented the Tak LEs with a 15mm Antares Elite 5-element Plossl (same basic 2-1-2 design of the 10mm and longer LEs). I have not yet fully flushed out if the 15mm Antares is performing as well as the LEs in this role, but hope to get back to doing that soon. The RKEs I really enjoy as they are only single coated optics which to my eye tend to render double stars a bit more cleanly and they also bring out colors very well compared to many multicoated fare. Just something I have noticed over the years comparing all the many eyepieces I've had. So always like to have one lineup of single coated eyepieces in the stall.
As a side note, for many years I have not really thought well of the Tak LEs in the planetary role as they showed a soft view compared to Abbes I had, especially the 7.5mm and 5mm LEs. Then one day while playing around with the LEs, I looked at their field lenses just to make sure it was clean before I put them away and they looked perfectly clean. But I felt like playing some more so cleaned them for the heck of it (and I rarely clean the field lens as they rarely get dirty in any way). So I took a Q-Tip dry and just lightly swiped the surface not expecting anything as I could see no dust. Low and behold it left a streak! To my surprise, the 7.5mm and 5mm both had this invisible uniform layer of grease on the lenses! So I cleaned them up. Then I took this other eyepiece I had purchased new some time ago during the summer months a few years ago that seemed soft to me, and it also had a same type of grease layer on the field lens. All I can make of it is that perhaps when things get shipped during the hot summer months that some of the rubber components or lens caps might outgass from the extreme temps that can be in delivery trucks in the hot sun, and that outgassing deposited that invisible layer of grease. At any rate, after tending to all the accessible lens surfaces on the LEs all of a sudden they became stellar planetary performers! So lesson learned for me to always clean the lenses, even when new or when they look clean!