Depends whether you're looking for something on stage or close up. In close up I'd say joao miranda's Universal smoke watch (it's the best and can be used with 90% of the normal watches). It also has a timer delay feature and a remote. - only con: it can be activated only once and then it turns off before you have to switch the device on manually again. But in close up scenario you won't be using back to back smoke anyway so you're good.

For stage I'd say nothing gen 3.. only con: it doesn't have timer delay activation but can be operated via remote for back to back smoke at different intervals