Ticket request system

Hi guys,

I need to get a system for managing a group of web developers. Something like a helpdesk system where people can post up their required website changes and these can then be assigned to developers.

This system should allow me to be able to:

1. Create tickets by web form (maybe by email also)
2. Generate detailed reports of tasks complete, outstanding, in progress etc for monitoring of staff / projects
3. Assign tasks to developers
4. Assign priorities to developers
5. Accept comments / progress updates to tasks

I think the above would be standard enough on any such system. Can any of you recommend a system either paid or open source that would be suitable for my needs?

I have come across osTicket which may suit my needs but I would be interested to hear any other suggestions.

Many thanks,

John.