Which perc card should I buy?

Hi Dell, I hope you can help me with my question.

I have a PowerEdge 2900 and I  have the RAID controller PERC6/i JT128 but I'm not sure about the model. We have to buy a new one because it shows FATAL ERROR every time we try to boot the OS.

I've seen that there are different models for this controller. I've seen the DX481, H726F, T954J. So my question is:

Which model should I buy? What are the differences about those models? I'm lost about which card should I buy.

I hope you guys can help me.

Thanks.