By far, the Nelvana series from the late '80s is one of the best-animated, most relevant TV cartoon series I've ever watched. I'm not just saying that from a collector's viewpoint, or because I have a soft spot for the bears. The morals hold up, it is cute and aesthetically appealing to young children, and is one of the rare "timeless classics" rumored to circulate out there somewhere.
While My Little Pony will always be my favorite vintage show, Care Bears Nelvana surpasses it in many ways, namely quality, continuity, and storyline. I'm a 15-year-old frequent watcher of both shows, mature enough to compare the two but still childish enough to appreciate them. Care Bears has virtually never had glaring mistakes like My Little Pony, and the animation is uniform and does not obviously change from episode to episode.
My very favorite Nelvana episodes were the earliest ones. These featured a diverse cast of characters and focused on what the Care Bears did best-helping young children in need. With a pastel color palate to die for and everyone's favorite bears getting at least a supporting role, these episodes are appealing for "collector-types"-those who like to see as many characters as possible, rather than just a few favorites.
The later episodes are not up on my favorites list. They feature a very limited cast of about 10 characters (including Brave Heart Lion, Bright Heart Raccoon, Cheer Bear, Grumpy Bear, Champ Bear, Grams Bear, Hugs 'n Tugs, and the dubiously-placed Treat Heart Pig, unreleased in the '80s and nonexistent today). The other bears and cousins were relegated to supporting roles and were most often not seen at all for several episodes in a role. The same thing is happening today with the Oopsy Bear cast, but I guess in the late '80s the call for core characters and rehauls was sweeping the toy industry in the same way as it is today. Why else would almost every major toy line redesign and narrow all at once? It happens about every 20 years...
Anyway, I digress. The most appealing parts of the later series were the more complex plots, dealing with parodies of existing adult stories such as Frankenstein and Star Trek. In addition, most of the characters got their own unique style, such as jackets, hats, a ponytail for Cheer Bear etc...that make them stand out. Not appealing to me, but probably for most it is considered cute.
I highly recommend the earlier shows, and somewhat suggest the later shows, but mainly for older kids. You have to appreciate core characters to see the true beauty in the later seasons. As for the earlier DIC series, not so much. Simple, poor animation, lame voices, derived plots and horrible sound effects...go with the Canadians on this one.