FPGA is boring, unless you know VHDL or something like that and would like to do some experiments.
And it is quite risky because it is hard to resell that FPGA board. I can sell my graphic cards to the gamers at any time.
With VGA it is more fun. I spent a lot of time writing automatic control script for my cards. It can't be compared with cgminer or other "professional scripts" but to me it is the best
1. PSU: 80plus PSU, trusted brands only
2. CPU: Cheapest, lowest power consumption cpu you can get
3. Motherboard: Cheap one with 4 pci-e slots at minimum, 3 pci-e 1x and 1 pci-e 16.