What mobile OS would be best for me?

Before I begin, I'd like to state that I currently own, and love, my HTC Arrive (WP 7.5 on Sprint) and I don't plan on leaving Sprint because the Sero plan is just awesome. I don't have any knocks against the phone but I'm looking for a phone that will do the things I want to do at maximum efficiency. I guess I should also state that I am an avid fan of webOS and am looking forward to seeing what the Open webOS project produces.

The use of my phone will be revolving around my life as a college student. I will be using SkyDrive since I own a W8 laptop at home but that shouldn't be a problem since SkyDrive is on every major platform. I will be using SkyDrive to open documents that I've saved. I love how SkyDrive backs up my photos and videos, can it still do this if I switch to iOS or Android?

I don't play very many games on my phone so those are a non-factor for me. However, I am very interested in apps that can help me study, I'm a biology major if that matters for content. I like to keep everything on my phone organized and orderly and value efficiency at a premium. I want to complete my tasks in the least number of steps without jumping from app to app; looking for synergy between the OS and apps that I would use.

The most common functions I preform on my phone are using the calendar/tasks app, texting/calling, twitter, web browsing, searching, and watching videos on Youtube/Netflix. I take pictures occasionally and the quality of the camera isn't too important for me. A excellent calendar app is essential for me, built in tasks/agenda/to-do list is highly preferred.

I am happy with WP so far but am wondering if you guys think there is a better device for me. Thank you.