Which is better Emerald or sapphire?

Answer.They are just different variations with different Pokemon to catch in each one. Pokemon Emerald is based around Rayquaza with a slightly different storyline, whereas Ruby and Sapphire focusd on the other 2 main legendaries., Groudon for Ruby and Kyogre for Sapphire.

Also, on Emerald your characters get slightly different outfits.

You can catch Rayquaza in Sapphire and in Ruby as well.