I had 2 of the 1054z, one at work and one at home.
Work then bought me a shiny 1000 series keysight to use, so I sold the rigol I had at work.
There are things I prefer the keysight for and things I prefer the rigol for.
With regards to encoder failures, the 7000 series keysight at work had 2 encoders fail. They were pretty easy to replace, but in your case with all the encoders dropping out, it definitely is something more than a dirty encoder.
I’ve got a few siglent bits of gear, but haven’t looked at the new offerings for a while, so I can’t advise on what is good. As others have mentioned, tautech is a siglent distributor and a wealth of knowledge, so any advice he gives on the siglent products is going to be 100%