Quick comments for you to ponder on when making your decision. If I have a socket set that is all one brand but a single socket is missing it does annoy me a bit having one socket that is a different brand "messing" up the otherwise clean lines of the set in its' storage rack. However if I have a different socket set that instead consists of several different brands of sockets (with visual variation all over) for some reason I could really care less what they look like visually and my primary concern instead becomes just making sure the sets are complete. In the back of my mind I also have a calm peace with the mixed socket set, because I know if a socket is lost or broken I can go almost anywhere and get a replacement quickly and easily. It is also much easier to find great deals if you allow yourself a lot more tools and brands to draw from.
I think it is human nature. If every one of my pliers were SnapOn brand with red handles and I had one blue handled Channellock plier in the same tool drawer it would annoy me a bit. I would feel the desire to replace it even though they work just fine, but having a plier drawer full of Channellock, Knipex, Klein, Craftsman, Gearwrench, of various ages, styles, and condition does not bother me at all. I actually take pride in the fact that I have stretched my dollar and found the best tools for the money and for the actual job instead of just buying the tools that all looked the same.
If you are the same way I am, I think you have reached a crossroads in your tool collection. You are going to have to decide whether you want every tool to match which will cost a lot of money to achieve, or else you will just have to dive in and instead start buying the best brands of each tool that you can find for the money. Start upgrading key areas and filling in holes in your existing tools. You will just have to trust me that as your variation increases, your issue with things not matching will fall to the wayside. Allowing things to mix and match will save you a lot of money in the long run, and you will be much happier if you ever lose or damage a tool. Losing a tool will signal more of a chance to possibly upgrade to a new and better tool instead of a mad search for the exact replacement to the one you lost.
Remember, even SnapOn changes the look of their sockets and wrenches occasionally, so just because you buy all SnapOn doesn't mean that a wrench you buy 10 years from now will look the same unless you find it used.