RtDL is the better game, but I think i enjoyed Epic Yarn more. Both are worth buying
Epic Yarn + Aesthitics/art style is top notch + Music + Most of the Vehicle segments are fun - Though a small number are NOT. - Can't die means it's too easy. A few parts, especially boss fights, could have really benefited from the sense of danger that the potential of death/failure would add. +/- Very relaxing and chill pace compared to most of the other major 2D platformers on Wii Discs.
Return to Dreamland + Lots of Kirby Super Star inspiration (multiple skills per copy ability, etc) + The Super Ability music always makes me feel like a badass. + Lategame bosses + 4 player co-op! [But 1P must be Kirby and 1P dies = retrun to last checkpoint] ? Again with the magical "120 collectibles" number? - I enjoyed the Dream Collection Challenge Stages (especially the Races) much more than RtDL versions.
Klonoa Dream Traveler of Noctis Sol (webcomic) September 26, 2012 on Shiftylook.com
You can't die, but losing beads makes it harder to get gold medals, and you can't complete every stage unless you get golds on boss stages. If you're just running through the game as fast as possible, then KEY is much easier than RtDL, but if you're trying to complete everything, I find KEY to be quite a bit harder.
Of course, if you factor in everything, including EX mode and True Arena, then RtDL is much harder.
~ The Vic Viper ~ "I have nightmares about hell, where all I do is add up numbers and try to have conversations with people like you."
The artbook does explain a little bit as to why they didn't allow deaths in the game (something along the lines of it doesn't fit the style), but w/e. Kirby has generally never been about being ridiculously hard.
I'm going to give my vote to Return to Dream Land since the gameplay reflects the more traditional Kirby games that we haven't seen in awhile (outside of the regular DS games like Squeak Squad and maybe Amazing Mirror despite the metroidvania like map system). It bothered me a little bit that Gamefaqs had a poll not too long ago about best Wii game and they left this game out in place of Epic Yarn. I like both games though.