There is no such thing as a good character or a bad character. That is a nasty little rumour that has been flying around since the inception of tamagotchis. If you have a look around, for every person that says you need to take "bad care" of a tama in order to get it, there is another person who has treated their tama better than their own dog and has gotten that same character!!! Don't be fooled into believing otherwise. Have fun with your tamagotchi and don't worry about it being good or bad.
Don't get one character (Masktchi , for instance) and let it die a lot of times. Because then no matter HOW you take care of it you will always get that character.