I'm not associated with them, but I have used them successfully for months at a time (better than most productivity software). The reason is it is well integrated and similar to email.
Asana is pretty bad. It takes forever to load, which sucks when people send you URLs to tasks/projects and you have to open them individually and wait almost 10 seconds for each to open.
Asana's start up time is just ridiculously slow. Probably the slowest webapp I've ever used. Also, you can't assign more than one person to a ticket, which is a pretty big limitation
JIRA also doesn't let you assign more than one person to a ticket. Could you expand on why this is a problem? I'm not familiarized with this problem space so I'm just curious.
The recent GitHub updates let you assign multiple people to reviews and such, but I find it's usually better to tag everyone you want to look at something. I don't think assigning something will send a notification.
www.asana.com
I'm not associated with them, but I have used them successfully for months at a time (better than most productivity software). The reason is it is well integrated and similar to email.