You could start by searching for all the other times design students have come up here asking for ideas, there are dozens, and some asked about lights.
I'd agree that there are many different needs, there's no one perfect bike light. The Cygolite HotShot is good. Personally I just bought a Knog Blinder 4V and it's my new favorite light. It does have a few quirks.
Pros for a "perfect" light:
USB rechargable - ideally just plugs right into the computer or a supply, like the Blinder does - but the blinder plug is a little tough to impossible to plug into some computers so a redesign couldn't hurt.
Multiple blink settings. Again, the Blinder has a good variety.
Wide angle - the Blinder gets this right - nearly even distribution of light. The Hotshot fails in this category, even 10 degrees off center the light falls off a lot.
Good mounting options - this is where the Blinder really fails - it has one option - clip around a seat post. Period. Now, if that's what you want, the Blinder's mounting is superb; simple and effective. but I'd like to buy one that could clip onto clothing/bag, or go onto a rack or seat stay.
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Work: the 8 hours that separates bike rides.