Which would win ra or blue eyes shining dragon?

Answer 1

Normally, Five-Headed Dragon will always win over a Blue-Eyes Shining Dragon, due to the 2000ATK difference.

However Blue-Eyes Shining can power itself up when there are dragons in its controller's graveyard. If there were 7, that would be 7x300 + 3000 = 5100ATK, high enough to destroy Five-Headed Dragon.

Answer 2

If you can get it out, then Blue-Eyes Shining Dragon would be the better choice, because not only does it gain an extra 300 attack points for each dragon in your grave (and if you properly summon Blue-Eyes Ultimate Dragon and sacrificed it, then it would be at least a total of 4200 attack points) but also can negate any card effect that targets it. The Winged Dragon of Ra is a good card if you can get it out early in the game, but after a while, it basically becomes dead, due to the fact that its attack points are determind by the amount of life points you have left. If you have, let's say, 2500 attack points left, then you would have to give up 2400 of your life points and Ra would be at 2400 attack. Even if you do get it early on in the game when your life points are high, A simple Hinotoma, Poison of the Old Man, or even the summoning of Achchacha Archer would cost you the duel.