I have always played a mixed bag, usually consisting of mizuno irons, Vokey wedges, and Taylor made driver/3w/hy.
When I got fitted (not going on a fitted rant here) I switched to srixon irons, Cleveland wedges, and ping driver/3w, Titleist hybrid.
In my mind, the mizuno brand has always been in a different, far superior, league than srixon. That being said, I have been really impressed with my srixon irons and consider them a better fit for my game without sacrificing quality.
As far as a “mixed bag” - I worked in the golf services industry imthrought high school and college, and would often purchase the complete sets from mizuno because the price was so good. I feel like having every club in your bag being the same manufacturer gives the appearance that you just went into a golf shop and bought a complete set off the rack. Having a mixed bag gives the impression you took the time to see what club is best for you.