One is not better than the other but both have things that they offer that the other does not or does differently or in some cases maybe a little better or easily.
The best way to go about finding which make may be right for you is to list your System specs, please include power supply, make/model and Wattage and resolution of monitor. and then list what you want from the card. What games do you want to play, any video editing or HTPC (watching films) etc. Also a budget is a good idea and where you will buy the card from.
That way we can suggest not just a make but a card that will meet your needs.