Citrus -- This challenge is cute. However, it is not a standout entry of yours, in my opinion. I feel like inventing a rule for the site is rather uninspired and impersonal. Like, a new rule on here? That's pretty boring, not playful. On the other hand, it could show that you are influential, if your rule were to be implemented.
Vespertine -- I enjoyed all those links

This challenge idea is the most unique and intriguing of all five, in my opinion. The idea of being a mentor to a new member is a great way to assess "top member" status. However, the downside is that this challenge would be incredibly difficult to implement. New members could be banned halfway through the challenge, they could leave ATRL after a few posts, or they could not respect you for whatever reason. They might not respond to Matty's survey, causing a headache for him. Also, each adopted member's personality would vary, so that could skew their perception of the mentoring experience. All-in-all, it would be extremely difficult to evaluate one's performance in this challenge. Still love the concept, but it is not pragmatic, sadly.
iHype -- At first, I was lukewarm about this idea. After looking at your entry, I could see it being an interesting challenge, actually. However, I will note (and please no one freak out at me for saying this) that this idea might be biased towards members with a larger resume and impact on the forum. Some ANTM contestants are using this platform as a tool to grow and understand themselves as members, and their year in review might not be terribly impressive compared to a more established member. Does this mean they don't have any top member potential? No. So, while it's a cute idea, I don't know if it would necessarily be fair. Also, the application process would already allow you to explain a lot of these achievements.
Marq -- What can I say, but great minds think alike, right?

I obviously love the promotion concept... however, I do think that requiring a promotional poster would be tough. When I thought about my promotion challenge, I wanted to make it so that anyone -- especially those with limited graphic design and formatting experience -- could show us their marketing skills: through social media posts, for example. I think some members would struggle with this challenge, putting certain others at an unfair advantage.
Those are my two cents. Cute ideas, but difficult to implement for the most part.