As somebody who does that drive multiple times a year and has for decades, there's no 'best roads'.
There's I-90 to I-79 to I-77 to I-26 to I-95 to I-4, shorter, quicker, more scenic but mountainous. Lots of stretches of little to no built-up areas, just the usual services at exits.
Then there's I-90 to I-71 to I-75. Much flatter, runs through more built-up areas. Also a lot longer and slower and routes you through several metropolitan areas notorious for traffic congestion.
If you want to take your time and smell the daisy's there's a myriad of secondary highways that will get you there too, but at the expense of time and may be a challenge with a bigger rig since they're often narrower winding roads that go through the center of many smaller towns.
Ted 'n' Laurie, plus Jackson (aka Deputy Dog, the Parson Russell Terrier 'fur kid') and, Rylie (who crossed the Rainbow Bridge June 14, 2012).