Take a look at my 2 machines:https://www.thingiverse.com/thing:4086006https://www.thingiverse.com/thing:3774108
I opted for aluminum extrusion frames with MGN12 Linear Rails/Guides.
Strong, stable, accurate.
Not all that expensive, as I got cheapo stuff from Amazon.
It all works great.
I'l do the same for my next build, whenever that is. :-)
Them's my .02¢
Your mileage may vary.