@brenavich980 PETG-CF is interesting with some products like 3DXTech CarbonX CF PETG but not very impressive with other CF variants like Atomic CF PETG (which I love but not for stiffness). Good CF filaments are often stronger in the direction of the CF strands but pretty much the same as the base plastic in the other direction. So layer orientation to the load is a big factor on whether the CF helps or does much of nothing. In addition, the CF does impact layer adhesion which can make the part fragile between the layer lines.
CF PC like Prusa’s blend is the ultimate in some ways but it needs a printer that can print it and it does have some issues bridging just because of the print temp. Manageable but not a set and forget thing for complex parts with lots of bridges. It also does have some shrinkage, though again manageable.