I started out collecting all mainstream Bruins cards from 1951 – 1990, and only want for one (the 1966-67 Topps USA Test Orr rookie, which is nowhere near mainstream).
Back then I completely ignored everything in the 1990s and 2000s. When the NHLPA kicked Topps/O-Pee-Chee to the curb, we seemingly had a dozen amateurs enter the market – ProSet, Score/Pinnacle, Donruss/Leaf, Fleer, and even Parkhurst made a comeback. Topps/O-Pee-Chee lowered their quality quite a bit instead of trying to compete, and flooded the market with junk (except for 1990-91 O-Pee-Chee Premier, which was nicer than the base product, and scarcer). But then this newcomer, Upper Deck, stormed the hockey scene and put everyone to shame with high-quality card stock, breakthrough photography, and true short prints. Eventually they took over several of these brands, most notably O-Pee-Chee, and muscled their way into deals with McDonald's, Tim Hortons, and Canadian Tire.
So, in more recent years, I've been able to collect every single Upper Deck and SP Authentic base card (including Young Guns and Future Watch) from 1990-91 to present. I'm missing a few variants but otherwise complete, and have lots of other team sets and parallels too. I don't know that I'll ever get around to documenting all the cards I have, because that's a lot, but I did want to highlight a short list of my favorites from the modern era. Some of these I tracked down via auction; most I pulled from pick-your-team case breaks.
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Willie O'Ree Ceremonial Puck Drops
I have all four variations in existence. The base variety is as scarce as the same year's Day with the Cup inserts, but the autographed version is much rarer (though they are both stickers):
2018-19 CPD-2 1 in 2,000 packs 2018-19 CP2-2 Auto 1 in 16,000 packs 2019-20 CPD-7 1 in 2,880 packs 2019-20 CPD-7 Auto 1 in 30,000 packs
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2014-15 Upper Deck Canvas #C225 David Pastrnak
The canvas insert was introduced in 2011-12 Upper Deck. Veterans are relatively plentiful, but rookies and retired stars are short printed. This particular card is not seen often, and certainly not with a PSA 10 designation (this is one of just 36).