Many rentals exhibit the same behavior. I typically wear earbuds or turn up the stereo when the 4 cylinder drone or the constant shifting starts to drive me nuts.
In real world terms, downsized, normally aspirated engines are the worst for overall pleasantness. I have 3 F150's, 2.7t 10sp, 3.5t 6sp and 5.4V8 6sp. The V8 is pleasant beyond words, the 3.5 sounds like a UPS truck, and the 2.7, while smooth, shifts constantly. I constantly pick the V8 for long trips.
In real world terms, downsized, normally aspirated engines are the worst for overall pleasantness. I have 3 F150's, 2.7t 10sp, 3.5t 6sp and 5.4V8 6sp. The V8 is pleasant beyond words, the 3.5 sounds like a UPS truck, and the 2.7, while smooth, shifts constantly. I constantly pick the V8 for long trips.