"Vote" on Dragon Type
Dragons are a powerful objective to take, but some champions benefit more from some types of dragon buffs more than others. I saw the idea floating around to let players have some influence over the dragon spawn, which was commented on by a dev as a good idea.
Here's what I propose: give players a way to "bait" and "repel" in dragons during the pick/ban phase so that the dragons they want are more likely to appear in a match.
Here's how it would work: In the champ select screen, you choose one of five types of special bait. Flavorwise, this could be each different dragon's favorite food. Then, you choose a repellent, something one specific dragon hates. Each player would do this, then the different types would be tallied up, adding all the baits and subtracting all the repellents, and the two dragons with the most "votes" are the types you see throughout the match, whose spawn order is semi-randomized. In the event that no dragon has any vote (e.g., both teams repelled the other's baited dragon), the dragon type is randomized like it was before.
This would give players a bit of strategic control over the importance of the dragon that spawns. Getting your team a dragon you can benefit from that the enemy team can't really use, or denying the enemy a powerful dragon for their comp, could be really impactful.
This system would also give the devs an important in-game statistic: dragon popularity. They could see directly which dragons people like, and which ones people would rather not have in their game. This data could be used to justify buffs and nerfs to the power of the dragon buffs. Ideally, each dragon should be just as powerful as the others, in their own way.
A possibility with this system could be the creation of "hybrid dragons", which have a mix of the buffs provided by other dragons. It would be a compromise when one team is split on the type of dragon they want, so that they can get the best of both worlds and/or a unique ability for each hybrid. For example, an Cloud + Infernal drake could be a "Smoke Drake", and would give a smaller amount of adaptive force and movement speed as either main type would, but might give you a small amount of extra movement speed when you damage an enemy champion. This would increase dragon diversity and let teams be very specific about the types of buffs they want.