the best answers have already been given, but depending on your prior knowledge, it might be a bit different.
first of all, do you have ANY experience in the IT security field? if not i'd go with sscp first. then again if your going for sscp just skip that and go for cissp straigth away. its covers all the topics more widely (someone once told me its a mile wide, but an inch deep) and in the long run, your cissp will help you further in your carreer then sscp.
if you have prior knowledge about security and want to go to the dark side
but have no knowledge about things like malware, virusses, etc. i'd suggest you go with ceh first. this will lay down the basics you have to know about all these things. ceh is perfect for getting that hacker mindset. it will also give some in depth experience with the standard tooling used. even though it is mostly focussed on windows tooling, the concept of the tooling is the same, regardless if its written for windows or linux.
when you get your foot in the tooling used, and the concept behind the tooling you can start on oscp. i think this particular one is significantly harder because of the (extremely) technical focus of the course. i must say i havent got the experience with this certificate yet, but i'm planning on starting it in a few days/weeks.
my opinion is that if you get through this in the order i described above, you are qualified to operate properly in a organization because of the knowledge you have got by cissp, you know the hacker mindset of a hacker by ceh, and have the technical skill to perform pentests by oscp.
in the future you can look at expanding your knowledge in the pentesting field by attending the ctp by offensive security or move over to the other side by going for certs like lpt.
good luck with your decision!