If you have the budget for it, an SO5 Pro is the way to go — so long as you are okay with the need to lubricate the linear rails.
An SO4 will reduce that need (only the Z-axis has linear rails), but will then require maintaining the belts.
As regards size, my recommendation is:
- if working on sheet goods/large projects, get an XXL or 4x4
- if working on boards, get an XL or 4x2
- if your projects/stock fit, get a Standard or 2x2
I picked a 4x2 when I had the chance, and managed to make it fit on a smallish table:
The other questions are:
- which spindle?
If you have 220 and are okay w/ managing a liquid cooling system, get an 80mm VFD, otherwise a 65mm VFD, unless you have a reason to get something else
- which dust shoe?
The stock Sweepy is awesome, but if getting a VFD, get a “Deep Sweep” — if working w/ sheet goods/flattish projects, then a Sweepy Pro may be a good fit, so long as you are okay with removing the bottom and shifting I up before each tool change, and then restoring the position of it after.