What is best tool to manage graphic design submission for bounty?

[honglu69]

Hello all,

we (NewEnglandcoin) are planning for our bounty for a graphic design.  Lots of graphic pictures will be submitted competing for award. 

I am new on this.  What is best tools out there to manage and review, and eventually decide the winner of a bounty. DISCORD dedicated bounty board?
dropbox?  etc.  Ideally several community leaders will view the submission and decide the first round. Eventually more community members should be allowed to comment and give feedback.
The decision of winner will be within a few group of members, but the participation is expected to be large among all members.

Thanks,