What should I buy?

Solution
Not all cards OC as well as others. Yours may be one of those. Some people might suggest adding a little more voltage; I prefer stock voltage myself as there is much less risk of damaging the card.
The R9 280 is not a substantial upgrade from what you have. Unless you're right on the edge of playability in certain games with your preferred settings, IMHO it is not worthwhile.
The Powercolor card is clocked higher, and will be faster. Sapphire has a mostly good reputation. Powercolor is less well-known. Despite their reputation, I know from reviews that Sapphire uses some less-efficient iron coil chokes on their cards; I'm not sure what Powercolor uses.
I've owned lesser cards of both brands, and had no trouble with either. That is a statistically insignificant sample, however in your place I would probably buy the less-expensive but faster Powercolor version. Note that it apparently uses a little more power (6pin + 8pin PCIe power cables needed, vs. 2x6pin for the Sapphire).
 


Ok so I have a 7950 but when I try and oc it to 1000mhz it just bsod and I was wondering if it would be easy to fix the error that comes up is IRQL NOT LESS OR EQUAL and I just want to know if that is easy to fix or just buy the r9 280
 
Not all cards OC as well as others. Yours may be one of those. Some people might suggest adding a little more voltage; I prefer stock voltage myself as there is much less risk of damaging the card.
The R9 280 is not a substantial upgrade from what you have. Unless you're right on the edge of playability in certain games with your preferred settings, IMHO it is not worthwhile.
 
Solution