I have all three. The V8, the 3.5EB and the 2.7EB.
The 2.7 is the fastest and the most fun. It's downright amazing with the 10 speed transmission (2018 and up) . The engine sounds great, is rev happy and willingly pulls at low revs. Will tow 3 and a half tons with ease! Even up steep hills. 20-21 mpg. If he gets a 2.7, get the 2018 and up. Sport mode sounds AND feels like a sports car. Really fun.
The 3.5 EB is nearly as fast as the 2.7. However, it sounds (groans) like a UPS truck and is not nearly as much of a pleasure to drive. It makes plenty of power and will cruise along and pull at low RPM all day long. It also tows wonderfully. It is a touch laggy and occasionally lugs a bit. 17-18mpg
The V8 is smoother, more refined feeling and sounds best. It's not as fast, and has nowhere near the mid range torque. However, I prefer the instant response of the V8 when driving like an idiot.... The V8 is still my favorite due to the very refined feel and instant response. 15mpg.