Only problem i have with Ra is when u sacrifice monsters for him he doesnt get theirs AP like it did in anime so u have to spend LPs... Slifer and Obelisk will be much better but Ra should best and actualy its worst...
In the anime ra does use life points to gain the attack it needs that's why you need to add a lot of health so that you have enough life and that ra has a lot of attack to go through with it
In order for you to successfully put points into the winged dragon of raw without using your life points you need to have Marik new skill level power of the tribute that will let you use the attack points of the monsters you sacrificed and will be transferred into Ra's attack and defense points