Spieth and McIlroy have gotten to this place in history with two completely different swings - both of which work for each respective player. Watching the 2018 Open Championship you'll see that Jordan's swing is unorthodox and somewhat unconventional, while Rory's swing is classic and more textbook.
Jordan's bent left elbow will sacrifice power in the swing compared to the full extension of Rory's swing. However, Spieth does this to avoid reliance on timing club-face rotation. Jordan also keeps his right hand under the club to help keep the face square longer through impact, so he's basically hitting a controlled and functional block shot. Compare Rory's swing where his right hand has completely turned over and consequently there's more club-face rotation.
Despite what others will tell you, neither swing is better than the other. It's clear Rory's swing works for Rory, and Jordan's swing works for Jordan. So take a lesson from both of these transcendent talents: owning your own swing is always going to be the best swing decision you can make.