lukesicari
formerly DW8
I would pick Ibaka. A big man like him is just so hard to find these days. He can block and play great defense in the paint and has a decent offensive game, which he can improve.
Now I love Harden as well, but his position is easier to replace. A scorer off the bench, you can find a lot of them. Not a lot in his class, but most of them will get the job done.