Here's a list of pros and cons about each game.
Magical Melody -
Pros:
-Lots of bachelors and bachelorettes
-Can play as either gender
-Can have a baby
-Can have a dog, cat, AND a pig
-Many villagers from various other games in the series
-Can go on forever
-You can own multiple horses
-You can always open the start menu and press Z to go home and sleep when it's late at night rather than walk home.
Cons:
-Marrying Jamie ends the game (many fans think of this as a con).
-Baby never ages, which can get kind of creepy after several years pass in-game
-Your baby
-At night, everything gets really dark and hard to see. I often had to open the start menu and press the Z button to go home.
-You'll have to buy all horses you get.
Another Wonderful Life -
Pros:
-Art and farming is more realistic
-You start out with a barn AND one cow
-You get a dog and cat (which do pretty much nothing)
-Your child will look like your spouse, and ages with each chapter
-You should get a free horse around the first summer.
-You can create hybrids of crops using a plant you get in Chapter 2 named "Tartan". (I have personally never gotten him, but I know for a fact that he exists.)
-If you have a second controller, you can plug it in to the third controller slot and then press Start for easy gold, or Z to get a bunch of random items. It randomizes every time you press it, so it's best to save anything you don't want to lose; you never know when you'll get to see it again.
Cons:
-Can only play as one gender
-Only three bachelors, which fans tend to describe as "the emo, the hippie, and the party guy". (This is a result of the game being a girl version of a game originally designed for a boy hero.)
-The game is divided into six one-year "chapters", and the years can get a little boring after a while. (Still, better compared to A Wonderful Life, where Chapter 3 had 3 years.)
-Finally: you die. But there IS a "Heaven Mode", which the original boy's version didn't have.