Boulder if you are into weed. Springs is a much more conservative area, and you won't find great stuff as easily, especially without a med card.
I haven't lived in Boulder for about four years now, but I did live there for 8 years, and although the larger stuff like The Farm and all the shops right off Pearl Street, Broadway and 28th Street are/were good stuff, they were also the more overpriced stuff.
I found Boulder Wellness Center early on in my search, and it was always the very best quality, and also on the cheaper end of things, in the 4 or so years I was dispensary shopping in Boulder, that was hands down the best place to go, and it is not somewhere easily found. 55th and Arapahoe, and not an obvious turn. If you take the time to find it though... well worth it.
Things might have changed in 4 years since I've left, but if it could maintain its quality for the years I shopped there, I don't doubt if its the same folks there, it is still the best you will find.