First off, I've used another brand controller before but never Arduino. I'm currently trying to come up with a way to read data from up to 8 RFID readers (https://www.parallax.com/product/28140) in order to activate a sequence. What Arduino board/setup would you recommend?
Let's see - what research have you done so far? 
Have you studied how these readers behave? Have you experimented with the one you have? That would be the first step in the process.
They advertise a 2400 Baud serial interface and sport a ~enable pin. You have to determine whether you wish them all to be "listening" at once, or whether you can switch rapidly from one to another. You need to do this as providing eight simultaneous serial interfaces is somewhat difficult with an Arduino alone (or indeed any other system). If you could switch between them, "polling" by enabling only one at a time to see whether it had data to send and then disabling it as you go to the next, that would make it practical to share one serial interface.
It may in fact be easier to use the USB versions with an eight-port hub interfaced to a Raspberry Pi.
It would of course be cheaper (one tenth of the price) and much easier to use the MFRC-522 modules which act as slave devices and are readily polled.
This is the beginning of my research... :o The controller I've used in the past only allows for 1 input. They do offer an input expander, but in order to use that I'd have to learn a whole new programming platform. I was thinking I'd try my hand at Arduino instead.
I did go ahead and buy an UNO to start playing with.
As for the Readers I plan to poll them to determine that the correct RFID tags are placed at the correct Readers. I will need to continuously poll them to determine if any Tags have been removed. In order to activate my sequence all tags will have to be at their correct Reader when polled. I plan to poll only Reader1 until I have a good read. Once the correct Tag is identified it will go to Reader2. If there is an incorrect tag at Reader2 it will go back to Reader1 to verify that tag. If it's still the correct tag it will check Reader2 again. It will continue this until all Tags are correct then activate my sequence.
I'm new to RFID and I appreciate you pointing out the MFRC-522 modules.
Sorry for being slow to respond, but my kids have started Baseball & Soccer so time is a precious commodity...