Effort versus reward in contests has always been off-balance, IMHO. Lower level players who need the rewards can't win them, and players with the resources to get to the top don't like the rewards they win.
I would like to see more of the rewards based on tokens, and more variety of items offered in the shops. That way, everyone could use their winnings to buy rewards that are more appropriate for their needs. I thought that was the original intention of the bazaar shop, but it hasn't been used much.
Also, contests should not be based solely on how much you can spend. I understand that contests are intended to drive spending, and I can't blame the devs for that. But alternating spend contests with something that everyone could achieve without spending would be nice. The first few orange and purple scrap contests were nice that way, except that players who aren't at a level yet to need orange or purple scraps got left out. And now, players who are looking for cyan scraps only get credit for the purple and orange they got by accident when grinding for cyan, or for the useless accumulations from the challenge raids.
I think that the contest progress levels should be set according to how much players should be able to accomplish at their current level. For example, on servers with 130 levels, the first progress reward should be based on what a level 30 player could reasonably be expected to accomplish if they use full (free) resources for the entire contest period. The reward at that level should be something that is generously appropriate for that level. Next progress reward should be set for the level 60 player, then 90, etc. That way everyone can achieve something, and if players want to reach above their normal level, they can spend. Progress rewards can be moderately generous, so that progress players feel like it's worth their time. Meanwhile, rank rewards can be more lucrative, so that spenders want to fight for them.
Yes, a system like that would mean that low level progress rewards are "useless" to high-level players. But no single prize is going to be appropriate for everyone, and a system like this makes the rewards more proportionate to the total population. The majority of people who express opinions here in the forums are high level players who are maxed out on everything, but that doesn't mean that all of the players in the game are at that level, or that everything in the game should be designed to benefit them, or that everyone in the game is using the same fifteen heroes and wants the same five rewards.