For me, Ross is the greatest embodiment of the Golden Age. He's sort of like the "American" Old Tom Morris in a sense. His designs have wonderful playing qualities and a generally classic presentation, and the routings flow effortlessly. More than anything, his designs have functional architecture. Each hole has a sound and interesting strategy that comes into play for a diverse range of skill and handicap, and his features are bold and commanding if not especially ornate. For me, his work calls to mind Woody Guthrie or Hank Williams - there's a simplicity in the artistry but a brilliance underlying the construction and function.
Maxwell's portfolio is less prolific. It's also more uneven, likely due to several factors both within and beyond his control. His work, at its worst, is mundane (see: Kentucky Dam Village). At its best, his work is transcendent. He was able to blend the functionality of Ross with an artistry that Ross simply couldn't match or didn't care for. That artistry gives his best works a post-modern feeling, and his best courses have a feeling of being "before their time." If you could find a well-traveled golfer who was somehow oblivious to places like Crystal Downs, Augusta National, or Prairie Dunes, I think you could easily convince him that those courses were built in the last ten years based on the quality and artistry underlying their presentation.
Of course, Maxwell doesn't deserve all the credit for those courses, and attribution is a final challenge with his work. He was certainly reliant on collaboration on many of his best courses. When I combine that fact with the fact that he had many mundane moments to go with some phenomenally transcendent ones, it leads me to compare his work to Tina Turner's - an artist with some dull moments who was heavily reliant on collaborators like Ike and Phil Spector (and even John Fogerty), but whose best moments simply redefine how we measure brilliance.
As for which I prefer, I've always loved Hank Williams' catalog, and I would likewise say that Ross is my preferred designer based simply on his consistency. I must admit, however, that if I had 45 minutes to listen to either a collection of Hank's best work or "River Deep Mountain High" followed by 40 minutes of silence, I'd probably choose the latter. Likewise, I might rather play one round at one of Maxwell's top efforts than 10 rounds on a collection of Ross' finest.