One downside of the I-10 route is that the road is very rough in Louisiana on the west side of Lake Charles and construction on the long Atchafalaya Basin bridge makes the lanes very narrow. I-20 is also somewhat rough in Louisiana, but not as bad.
Depending on which route you take, if you are not in any hurry, I would consider looping around Dallas/Fort Worth and Houston to avoid lots of heavy traffic. Keep in mind that non-interstate major roads, state highways and secondary roads usually are pretty good in Texas, though you will experience stop lights in towns.
I, myself, would take the route Google suggests if in doubt. I do avoid the stress of big city traffic with my RV if I can help it and have the time.
