Which is the best "God Card" ?

Depends what you like. With Slipher his attack is stationary, equaling all the attacks of the sacrificed monsters added together, and thats it. Slifers is 1000 for every card in your hand, so if you have 6 that's great, but if you use your hand and have 1 or 2 or even no cards it's bad. Im not sure about Obilisk.

The answer is Ra simply because it's hard to get rid of once it's on the field yes slifer has the unlimited attack ability but it's hard to get an keep more than 6 cards in your hand an obelisk tribute ability is good but it cost your powerfull monsters for it to be worth while although he does have the constant 4000 attack which helps an the tokens but still Ra wins hands down, now if they had the special abilities they have it the cartoon slifer wins just because of his ability to destroy any new summoned monster. So a better answer would be it depends on the deck your going to use with the god card.

Obelisk: Ra And slife can be destroyed with effects. While Obelisk can only be destoryed with cards that don't target...

Obelisk=strongest
Silfer or Ra=Muka-Muka ability
Silfer or Ra=???

Obelisk is the best and I know that for sure because I have it and I also have ra and slifer (how lucky am I ;) ) so basically you can use ra and slifer and even obelisk but they can all be destroyed by dark hole or lightning vortex because neither of those cards target the god card alone!! But obelisk has the effect of tributing 2 monsters to destroy all opponent's monsters (although it cannot attack that turn). With ra you can give him all of your life points up to 7900 (or however much you are playing with) but even 100 damage by card effect to you're life points will kill you!!!!!!!! Slifer has a luck chance because you should have plenty of set spells/traps to destroy any effects you're opponent activates. That will take away cards from you're hand, thus making slifer lose atk. Obelisk stays at his 4000 atk and has good effects. This is a simple choice. Hope this helped

Never Ra . Ra can easily be destroyed by dark hole and lightning vortex. And so can the other gods. But just imagine if your opponent has draining shield? Well than you just gave them 7900 lifepoints. And then what is also TERRIBLE about Ra is that you usually have a few hundred lifepoints left if you want to make it really strong. Just a little card that attacks your life points directly will kill you, such as raging flame sprite. Or even a spell like thunder short will kill you. I have already said that obelisk is the best in the above comment.