The cartoon has that "it's so bad that it's good" kinda feel which I'm a fan of. The CD-I games are just annoying even though I do say some lines from them. I haven't played the CD-I games but judging from all of the videos I have seen, the games don't look fun. Plus the games are over $80, you can get all of the episodes for $15 or you can just watch them on youtube for free.
There is no clear victor here. Both are terrible and have sullied the Zelda name. To the untrained eye, the CD-i games are more horrendous, but think about it this way. The Zelda TV could have actually become rather successful if the right team of writers, voice actors and animators worked on it. It probably had some potential to be a half-decent show, but fell flat on its back because the execution was so poor. The Philips CD-i games were doomed to a terrible fate the moment work began - the budget was meager, the backgrounds were hand-drawn, and the games were created for one of gaming's worst consoles by non-Nintendo developers.
I would say they both be abolished to a bottomless pit lined with fire, then fished out so they can sit in the core of a rotten apple. Then the apple will be impaled by a stake, along with the CD-i games and the DVD copies of the Zelda TV show, and then roundhouse kicked by a 50-foot tall Chuck Norris (although we know a gigantic Chuck Norris can't actually exist, since the strength of muscles is related to cross-sectional area and mass is related to volume, therefore Chuck Norris would collapse under his own weight just as King Kong would).
The Zelda cartoons are NOT the worst thing that has happened to the series. People that grew up on the classics would most likely enjoy the cartoons for a nostalgia effect. The CD-i Zeldas however should just be long forgotten.
The cd-i games are much worse. I never played them, but I looked them up on youtube to find out how bad they were. Game Informer also had a few things to say about them when they did there Zelda cover story. From what I know, the cd-i games not only fail as Zelda games, but are an utter failure as a game in general. The Zelda cartoons weren't all that bad. They were basically a common 80's cartoon with Zelda characters put in. They were actually somewhat funny too. Too bad they weren't done a little better or they might have actually been pretty good.