That page is quite out of date.
The best of the Corsair PSU are not included (AXi, HXi, RMi)
The TX and GS lines are discontinued.
It also mentioned that most Corsair PSUs are made by Seasonic. That is false. The best Corsair PSUs are made by Flextronics (Axi) and their second best (HXi, RMi) are made by CWT. The only Seasonic made units still left in Corsair's line up are the AX lower than 1200w, and I am not even sure the regular AX line is still alive.
Given that the regular AX PSUs were the product line with the highest RMA percent of any Corsair PSU, you can see why they moved toward other OEMs.
To the OP, the CX series is a CWT design. Nothing fancy about them, other than they are still the best budget PSUs on the market. 80+ bronze, some semimodular
The CS series is made by great wall. Great wall used to make the OCZ ZT and ZX series, PSUs that got a lot of positive reviews. It is an premium budget line. 80+ gold, semimodular.
In your question between RMi 650, RMx 550 and eVGA 650 G2, grab whatever is at the best price, they are all 3 fantastic units. My nod goes to the RMx 550W as will save you some money, and a single 12V at 45A will be plenty for anything other than exotic crossfire setups.