I've owned both. Drove a 5.7 hemi Ram for 5 years and currently drive a 3.5 ecoboost F150. General driving feel between both is relatively similar. Both are smooth powerful engines. To get power from the 5.7 it needs to downshift to get the RPM up, but it does move and tows very well. The 3.5 Eco doesn't need as much RPM to make serious power, but once on boost, it's power is awesome. It also tows very well.
The Ram averaged around 19mpg in the rural roads around here and around 15 in city driving. Towing my enclosed cargo trailer, that dropped to 12, regardless of speed up to about 70. Empty highway cruising below 75, the Ram managed a solid 20 mpg which is quite good for a V8 IMO.
The 3.5 Eco averages around 20 on the rural roads around here, about 18 in the city, and a solid 24 during highway cruising below 75. Towing the same trailer, mileage was 15, to slightly above that.
The Ram had the 4 corner air suspension which was really awesome. When loaded, or towing that system automatically added pressure to the rear to keep the suspension level, zero squat. Fit and finish was comparable between the two (same trim levels on both, Limited). Despite using a top quality motor oil, (and I'm not going to get into a which oil is better discussion), the 5.7 began to demonstrate the often discussed lifter tick at idle. In that vein I have heard 2020 MY Rams also ticking loudly at idle at fuel stations, so at least into 2020, that issue is still extant on some Rams. The German designed 8-speed on the Ram is a fabulous transmission.
The Ford/GM designed 10 speed in the F150 in my truck is also superb. Turbochargers on the 3.5 Eco are a consumable, which is something everyone contemplating purchasing a turbocharged vehicle ought to realize. I don't consider that a detriment, just a consideration. I'm not into loud trucks, so exhaust sound between the V8 and V6 is not an issue. The 3.5 is a DI motor, however Ford has equipped the engine with a dual injection system. DI is used for starting, but port injection is used for most normal driving. When additional power is called by way of the throttle, the direct injection takes over. This effectively eliminates valve and port clogging from baked oil mist from the PCV system which can be an issue on a strictly DI engine.
V8 or turbo V6, are both great trucks, and each has it's plusses and minuses. I'm completely satisfied driving and towing with the F150, and have been for the past 2 years.