What are good alternatives to Justuno for on-site messaging?

[TMD_Shop]

Hi, 

Looking for recommendations for an app for on-site messaging that can be triggered by past behavior (e.g. purchasers, non-purchasers returning visitor, new visitor, etc.). We already use Attentive for lead-capture so looking for an app just to display on-site messaging. Something similar to Justuno. Besides Justuno, any other recommendations?

Thank you.