Capitals
Avalanche
Red Wings
Also one-time winners in the last 15 years.
But the Red Wings were multi-Cup winners, their last one just happened to be the first year of that 15 year period. I count them in the repeaters club.
The Avalanche just won last year and look like they can easily win again.
The one-time winners should be considered the Blues, the Capitals and the Bruins. But the Bruins appeared in two more and the Capitals have the second best player of the era/second greatest goal scorer ever. The Blues are the team that is the true "one-off" and "anything can happen if you play well and the chips fall in your favor," team. The others are all semi-dynasties with dynastic-level talent that just haven't gotten all the breaks, mostly because they've run into other dynastic teams.
If one wants to argue that we can't become the Penguins because we don't have Malkin and Crosby and can't get said players at least we should target becoming like the Bruins.
Lucic (in his prime), Krejci, Bergeron, Marchand. Blake Wheeler and Tyler Seguin were on the early teams (1 cup win, 1 finals loss). David Pastrnak on the later team. Nathan Horton before he was injured. Mark Recchi as the MSL of the team.
They were loaded. We aren't like them yet, not even close. We need Laf and Kakko to become Marchand, Seguin, Wheeler, etc. And we need more talent, way more young forward talent.
Their D also featured Chara, Krug, Hamilton, and McAvoy along the way. We have Fox.... and... well, Trouba sucks in comparison to those guys.