Compare and contrast.
I think you mean contrast and compare.
Contrast: Your premise is false. Some brands are made all year.
Compare: But the springtime ones are best. Much richer.
My favorite is Pabst (I forget the brand, but it has a billy goat on the front. What a kick.)
I always like the German beers imported around Oktoberfest time. Lots of choices you don’t see other times.
Some of the microbrews are good. Pyramid has some, but distribution is spotty.
Baderbrau (brewed in exotic Elmhurst, Illinois) used to brew a kick ass bock beer. I don’t know if they still do or its a seasonal thing or if its gone forever. I’ve been away from Chicago too long.
I’m sorry, but this forum is for questions.
The OP is a fact, and not debatable! 
**OK, now CLASS of beer or brewing only **
(You may vote early and often, but don’t leave without buying a round!)
REMEMBER This is an Exhibition, not a Competition - NO WAGERING
(I think we’re still in business with the answers we got so far.)
Just a recap-
Oncle Bière…year-round bock beer.
Show_Biz…springtime bock beer.
X-files…German Imported Oktoberfest speciality beers (and Lance Turbo…kick ass bock beer from Chicago
Oncle Bière…another grand (and under-imported) class: Danish dark beers
Actually, to go back to the OP. Here in Central Wisconsin, Point Brewery used to only brew Bock for a short portion of the year. Very tasty, and the supply was usually gone quickly.
Now they make it all year round and I don’t know anyone who drinks it. The anticipation is gone, and it just doesn’t taste as good. Whether that is psychological in nature is a matter for debate. In any regard, I wish they’d go back to the good old days of “bock season.”
This tradition is not widely recognized here in AltaMéxico
Like Carta Blanca
“No other beer in México achieves more history and tradition than Carta Blanca. It was the first brand to be brewed by Cervecería Cuauhtémoc in 1890 and also the first Mexican beer to be exported, in the 1920´s.”
Also Bohemia
"Bohemia was launched into the market in 1905 and is considered to be one of Cervecería Cuauhtémoc Moctezuma´s finest products. Its name refers to the great brewing region of Czechoslovakia. "
Also Noche Buena
“There is no other beer more eagerly awaited in Mexico each Christmas than Noche Buena. Cervecería Moctezuma began brewing Noche Buena in 1924, as a special edition beer to give away as a Christmas gift to friends.”
Me too Gazoo! I lived and tended bar in Point for 5 years, just as year-round Bock was beginning. Invariably, around mid-June, people would begin to ask " Why do you still have bock on tap? Nobody’s going to drink that old crap." Trying to convince them that it was 'new ’ bock was nearly impossible. Also, they changed the recipe for the bock so that it was hardly distinguishable from the Amber. Nothing like the old thick, syrupy, bitter bock of old.
I only drink light beers. I want something I can stay with all evening.
Lately I’ve fallen in love with hops. Lots of hops. Hops, hops, hops. IPA, ESB or more. There’s something out here on the west coast called Anderson Valley Brewing’s Hop Ottin IPA, which does the trick.
I am also very partial to strange Belgian things-- not so much the lambics as the difficult to describe, estery, coriander-hinted but not technically a witbier beers. The nice people who make le Guillotine and Delerium Tremens have a glorious new one out called Delirium Nocturne. Yum yum.