Didn’t see such a topic here on the forum, hope I do not duplicate anything - do you generally consider some countries to have a quality stamps that stand out among others?
I’ll start!
For me French stamps are really cool, they often use this old fashioned engraving style and I really appreciate it.
Chinese (PRC) never disappoints. They use a lot of their traditional paintings as motifs for their stamps, often interesting shapes (like a traditional fan).
Japanese - variety of topics, often minimalistic, cute or just very esthetic. Little pieces of art
Jersey Island - surprisingly this small territory contributes a lot in stamp design IMO. They often use wonderful photography
Czechia - they have a certain style which they use for most of their stamps, making all designs very coherent. Many of their stamps are either artistic or cute
USA - a great variety of themes, often very creative. I only regret they’re mostly stickers
I really love the Japanese and Russian stamps. In addition to the illustration and designs, I love the variety of shapes they come in. It’s so fun.
I did notice Canada does have at least one cute shaped sheet.
I have also received some lovely mini sheets from India and Russia. Those are really interesting to receive. I’m sure other countries have them but those are the only ones I have received.
-UK, great variety of topics, beautiful designs that really tell you someting about British culture
-Belgium, also so much about culture, food, and often very unique sheets or shapes
-Russia, beautiful illustrations, showing a lot of variety
-P.R. China, they just have something unique about them, a certain way of drawing, very beautiful
-USA, even though sometimes the design is simple, you instantly know what it is about or what it tries to tell
That is just some of them, I also like Czechia, France and Turkiye but didn’t have anything to say apart from they have beautiful stamps
Like you, I think France has some impressive designs. Austria is another country. Sad to say, I find many US stamps uninspiring. The clowns over there love stamps featuring cartoon characters, race cars, dinosaurs, etc.
I agree with you @cliffside, they are fun when mailing to people with children or special collections, but overall I’m usually disappointed with my stamp options. I much prefer the lovely stamps I see incoming!
Not to be biased, but Portuguese stamps are also beautiful and of quite good quality. in terms of production and design, my favorites are from Australia and Singapore.
I am from Japan myself and love the old and older Japanese stamps that are not adhesive / stickers. At stamp shows in Japan, we can buy many of those old mint stamps for the same cost.
Personally, I love Asian stamps like from India, Sri Lanka, Indonesia, Malaysia, Laos, Thailand, China, Vietnam, etc.
As for Europe, I was amazed with the stamps from Czech Republic and Slovakia.
I really love Japanese and Taiwanese stamps, but I think New Zealand does the best Lunar New Year designs in recent years, and I’m very grateful that here in Australia we get both a huge amount of designs and always the option of both self-adhesive and gummed, and we are lucky enough to get designs featuring our overseas territories (Norfolk Island, Christmas Island, Cocos (Keeling) Islands, Australian Antarctic Territory), which are often stylistically different to regular Australian stamps and can still be used in Australia. I think AusPost is about due for some more cat-themed stamps, though!
)
Australian 
stamps. They, so often, feature their unique Flora and Fauna, which is my favourite kind of stamps! 
stamps very often, even though they are often illustrations and I MUCH prefer photos (except Blue Cats and Lou Paper! 
and French 
stamps very often absolutely lovely.
