Open air cooler: offers up to 10% better performance than with blower type and runs at cooler temps, but it would be the best to have additional fans for the air inside to be circulating (hot out, normal in).
Blower style cooler: take it only when the case is horribly ventilated and you think you might get thermal throttling. Blower type cooler takes air from the inside and blows all the hot air outside (open air - takes from the inside and blows back to the inside, so additional fans help a lot), so other components inside the case don't get the heat from the GPU.
http://i.gyazo.com/3573246899fb475e450fbe40759bbaf7.png
All in all, take open air cooler for noticeably better performance and lower temperatures and blower type only if you think your case is already hot enough and the additional heat from the GPU will break the limit and cause thermal throttling.