I have been an amateur astronomer for long enough that according to the 25-year definition, nearly all of my eyepieces are classics, so I am not going to list all of them. My favorites are:
(1) For observations where a particularly wide field is either not necessary or impossible (no 2-inch focuser): Brandon 8, 12, 16, 24 and 32 mm.
(2) For wide-field, long focal-length views, where a two-inch focuser is available: Brandon/Vernonscope two-inch-barrel 32, 40 and 48 mm.
(3) For wide field at fast focal ratios: 20 mm Meade Research-Grade Erfle.
Now let me explain why I list these eyepieces: I should mention in passing that I use more modern eyepieces as well -- notably including Explore Scientific 82-degree-field units for wider fields, and TeleVue 2-4 mm and 3-6 mm zoom Naglers for high magnifications.
I am particularly fond of deep-sky observing. For that purpose I make most use of exit pupils of about 4 mm and about 1.5 mm.
At f/9 to f/11 -- Schmidt-Cassegrains and some refractors -- those exit pupils are well matched by 40 mm and 16 mm eyepieces. The Brandon/Vernonscope eyepieces are superb and all work well at these focal ratios, and when I am using a 1.5 mm exit pupil I am generally looking at specific objects that do not require a particularly wide field, hence the 1.25-inch barrel of the Brandon 16 is no real restriction, even at 244x with my C-14.
At around f/8 -- many refractors -- the same argument produces 32 and 12 mm focal lengths, and again I use the Brandon/Vernonscope stuff, with the two-inch barrel 32 mm used with two-inch focusers.
At f/5 -- think rich-field telescopes -- the Meade 20 mm Erfle has worked well for me for a 4 mm exit pupil. I do have a 20 mm Brandon wide-field which also works, but I bought that only recenly so have mostly used the Meade for this purpose. I have played with several eyepieces to get the 1.5 mm exit pupil at f/5, but most often use f/5 for rich-field work, so am not listing them.
At f/15 or thereabout, I don't have a really good solution for 4 mm exit pupil views, but the Brandon 24 mm does well for the 1.5 mm case.
I don't have any classic eyepieces that I use regularly for planetary or double-star work: For that stuff I use more modern types, like the zoom Naglers.