The point is while you can do generic verilog or VHDL development on free tools, as soon as you want to implement it, you'll need the vendor's proprietary tools, regardless where you turn to.

Xilinx with Vivado is by far the worst. If you think Windows and Office play the vendor-lock-in hard, Xilinx plays it way harder. Once you develop with their stuff, you'll have a hard time getting anywhere else. And Xilinx is rather unfriendly to smaller shops. Yes, if you buy millions of chips or you are at a university, they blow sugar in your ass. Outside that, they happily fuck you over.

If you want to be as free and open as possible, Vivado is by far the worst choice you could do.