Here is my thinking.
The Cowboys basically had a choice here. Ramsey, Elliot, Tunsil, and Bosa.
Ramsey
From a defensive stand point, he makes sense. A Carr replacement and a great athletic player. From a playing stand point, I'm not sure he is going to translate into a super star CB. The guy is just missing instincts or something. He will be decent, but not great. From a drafting stand point, he is not an instance impact player for the Cowboys. The Cowboys lack any pressure on the defensive front. This means Ramsey (or any DB) has to cover longer and well. That helps nobody but the opposing offense. Ramsey would have minimal effect to the Cowboys defense this year.
Elliot
Without a doubt, an instance impact player. Both from an offensive and defensive stand point. On offense, he will wear down a defense and keep drives alive. From a defensive stand point, the less the defense is on the field, the better situation it is for the defense. (rest and the opposing team can't score if they don't have the ball) From a draft stand point, you don't want a short career player that high in the draft, but if the Cowboys manage him well. Elliot can play 10 years and if that happens, he is without question well worth the high draft pick investment.
Tunsil
Wow, this kid could have easily went top 5, but there is no antidote for stupidity. Once stupid, always stupid. I don't care how much of an athletic freak you are. You also must be a football player and have at least a pea sized brain to be successful at the NFL level. This guy... yeah well. Pass. (I had no idea how stupid he actually was until draft day)
Bosa
Instant impact player, though I don't think he will be anywhere near as good out of the gate as the draft hype machine made him sound. His greatest strength is holding his point of attack. He shows some laterally measurable s that sound good, but you don't see them in his play. That would suggest he can be taught to the skills that exercise those abilities. He doesn't have them today though. From a draft stand point, we need a better front and he would help. Especially against the run, but I think he will be good player, but not a great one.
The end result is that Elliot made the most sense both short and long term. He is a generational talent in the mold of some of the workhorse backs of the past. If the Cowboys manage his touches correctly, this guy with this offensive line will join the Cowboys running back pantheon by 2026. Elliot was the right pick at #4.