JustUno is easy to use. You can create your account and start collecting opt-ins (whether that be SMS, email etc) within minutes. They provide account managers if needed, but it is totally self serve as well.

Easy to make basic lead gen or popups advertising promotions. Powerful rule based and design promotions are possible.

I think the platform works really well and integrates with all of our services and other software. I think their upcharge for strategy implementation etc was a complete rip-off based on feedback from my marketing team.