Solver preference - CFX vs FLUENT
 

In the "Defaults" section, there is an option for CFX or FLUENT. I have found that if I set it as FLUENT, often mesh would be successfully created while I get errors for CFX option. Can I use meshes created using FLUENT option in CFX? Also, is there any advantage of using CFX setting for CFX?

0.272 transition ratio
 

The Fluent mesh uses a 0.272 transition ratio, whereas the CFX mesh uses 0.77 transition ratio. This means the meshing program tries to use a more steep transition with CFX than with FLUENT. The CFX solver is more flexible and may solve a mesh with higher rate at which adjacent elements grow. If your mesh only works with the FLUENT meshing it means that less smooth transition does not work. Be careful about this and check your other sizing controls. Unless the geometry is very complex, I would not expect this issue to arise in the first place.

Nevertheless this might be OK and CFX may still work with the FLUENT style mesh. Try it and see whether the solution converges. If it does, check mesh convergence — compare your results at different mesh sizes, plot H-convergence plot, evaluate grid convergence index.

The exact differences between FLUENT and CFX meshing are documented here and there more detail.