I'm going to agree with S3rius, you would have less overhead with an actor as the base, but unless you are running out of memory or processing power, units are going to be a lot simpler (you technically should be able to do everything to an actor that you can a unit, but a lot of the behaviors will be built into a unit, and you'd have to code from scratch for an actor)
The only other idea in terms of simplicity I have is I know there's a "beam" type effect used for things like the Void Ray beam. If you can change properties of it, you would have it mostly done... but it may take you longer to figure out how to mess with it than it would coding up your custom unit chain.
I'm going to agree with S3rius, you would have less overhead with an actor as the base, but unless you are running out of memory or processing power, units are going to be a lot simpler (you technically should be able to do everything to an actor that you can a unit, but a lot of the behaviors will be built into a unit, and you'd have to code from scratch for an actor)
The only other idea in terms of simplicity I have is I know there's a "beam" type effect used for things like the Void Ray beam. If you can change properties of it, you would have it mostly done... but it may take you longer to figure out how to mess with it than it would coding up your custom unit chain.