In my humble opinion everything Xilinx is doing for SoC development is way better than what Altera is doing except for the silicon itself. For our needs Arria 10 SoC silicon was way more capable than the Zynq 7000 devices, and we did not have time to wait for the Ultrascale+ MPSoC stuff. I hate Qsys. Vivado is a much better thought out tool and much easier to use. It handles IP in a well thought out and consistent way. Qsys not so much. Xilinx's support in terms of reference designs, on-line training, the Xilinx user forum, documentation (their DocNav tool is fantastic), etc., all much superior to what Altera offers. Not sure how things got to this point. Five years ago I would have described the situation much differently. Xilinx's 7 series devices and Vivado tool suite were both game changers and they caught Altera with their pants down. Arria V was a complete disaster (IMO) with a slow fabric and no support for DDR3 read and write leveling (so no DIMM support). I could continue but won't. Needless to say I'm very disappointed with Altera after many years of being a happy customer.