For Hermes is the Birkin, Kelly, Constance, and other models in rarer colors/materials.
For Chanel it is mostly the classic flap in black and the classic boy bag, also in black. Some runway pieces and rarer colors for both model do retain their value a lot but I mostly see black color for both go for big bucks.
I think you will get an idea if you look at reputable on line consignment stores like www.collectorsquare.com
Hermès holds its value on some models.
Same with Chanel and LV.
Fendi... yes, If you buy a Peekaboo..
ime, just certain styles from hermes, chanel and lv... and vintage styles from the other brands might be worth a bit more than their regular stuff. usually the exotics have a good resale too, or at least hold value, like ostrich, python, stingray, etc. there are lots of hermes that don't hold value, the same with chanel and lv - just because it comes from one of those 3 doesn't make it a great return for money spent, it really needs to be a true classic piece in a very standard design and color. the more bells and whistles and color, the less it'll hold value. be boring and classic and stick to those 3 and you'll at least get some of what you spent back. bags are not an investment though, at least not like they used to be when women held on to them for 20+ years ; these days we turn them over too soon and fashion houses produce too many for any to appreciate well. bit of a tangent there....