Trubisky was always considered the more long term sure bet based on style of play fitting the NFL prototype. He was raw but had great accuracy in college and fit a very Steve Young type mold. His mental acumen, toughness (ability to ignore the criticism) and leadership deficiencies were underestimated.
The Bears and their fans did him no favors, boo'ed before ever putting on the jersey and surrounded by coaches that either had no clue or gave no shits about him.
Fields floor and ceiling are so much higher than Trubisky's ever were and style fits the modern NFL. I liked Trubisky at the time because pre-Mahomes, the guys that would run with some regularity always seemed to stress defenses but either break down or fall short as passers(Tarkington, Cunningham, McNabb, Vick, Newton, Winston, Manzel, RGIII) .
I will hope and cheer Fields on as I did Mitch until he isn't a Bear. I have much less doubt about him being good to great. In fact his 6'3" 225 frame , athleticism, passing ability, level of competion, and experience, I would say, has not ever been seen coming out of college. Mahomes shocked the world, and I can't help shake the feeling that the guy drafted at #11 is going to be like the guy drafted at #10 4 yrs ago.