The "tone fatigue" of using one synth over and over is normal and happens to everyone. You can pick the best overall synth for your tastes, and if you use mostly that synth, your taste will eventually lean toward "anything but".
Until you sell it, that is... and then later you'll hear one and wonder why you ever sold it in the first place.
The only remedy for that I've found is to have enough different instruments that some of them sit neglected and wanting for long periods of time. Then when you get tired of one, you pull one of the old favorites down and remember what drew you to it in the first place.
Variety is the spice of life.
The alternative to the remedy is just ongoing G.A.S. where you just buy something new to get the "variety" fix, then get bored, then sell it on... then maybe re-buy stuff you used to have then let go, yada yada. It's a vicious cycle, and for me at least was cheaper in the long run to keep a good rotation of instruments.
Part of the joy of new synths is the learning and discovery that comes with them. When you put them away for a 2+ years at a time, then revisit, you get to learn and discover and explore all over again.