Which USB 2.0 chip to interface PC with FPGA?
The FT2232H would probably be a good choice.  The FT2232H provides two interfaces, which are configurable for UART, FIFO, and JTAG, among others. So you can use one port in JTAG mode to configure the FPGA (using openocd) and another port in FIFO mode for reasonably high speed data transfer.  The FIFOs can run in async mode (8 MBps or 64 Mbps) or synchronous mode (40 MBps or 320 Mbps). How much bandwidth do you need?