I'm going to compare them and you can tell me what you think.

Goldd, Wu-Lord of Dark World

LV5/Fiend/2300/1400

If this card is discarded from your hand to the graveyard by a card effect, special summon this card to your side of the field. If this card is discarded form your hand to the graveyard by your opponent's card effect, you can select up to two cards on your opponent's side of the field and destroy them.


Positive:

1) can kill a Cyber Dragon
2) gets summoned to the field if it is discarded by an effect
3) gets summoned and you get to destroy 2 cards on your opponent's side of the field (which will most likely give you complete and utter field control)

Negative:

1) 5 star and can lock up hand
2) has only 2300 attack


Siliva, Warlord of Dark World

LV5/Fiend/2300/1400

If this card is discarded from your hand to the graveyard by a card effect, special summon this card to your side of the field. If this card is discarded form your hand to the graveyard by your opponent's card effect, your opponent selects 2 cards in their hand and returns them to the bottom of their deck in any order.


Positive:

1) can kill a Cyber Dragon
2) gets summoned to the field if it is discarded by an effect
3) gets summoned and your opponent selects 2 card from their hand and puts them on the bottom of their deck

Negative:

1) 5 star and can lock up hand
2) has only 2300 attack
3) the cards don't go to the graveyard


Siliva has more negative things than Goldd and I think Goldd is less situational but there are many more cards that can destroy monsters than can get rid of hands without doing damage.

So which do YOU think is better?

They are equal. Both effects rely totally on the situation to determine which is better, and with otherwise equal stats, there's no other way to compare.

How is that a negative?

It depends on what kind of advantage you are looking for. If you want field advantage, use Goldd. If you are looking for hand advantage, use Sillva.

By the way, it's Sillva, not Siliva. ;P

It was blurred on the site.