Thank you for your question. For an algae reactor we would recommend either the medium fine chaeto or the thick chaeto macroalgae, they are still the best fast growing and uncomplicated macroalgae species, perfect for the nutrients export.
The fine Chaetomorpha we would just recommend when the water flow is not very high.

For the reef tank it depends what kind of look you are going for. If you prefer a planted reef tank you can of course use all macroalgae species, including more invasive ones like Caulerpa Racemosa, Caulerpa Prolifera and Caulerpa Taxifolia.
If you have a mixed reef tank with corals you might want to be more careful with those macroalgae species, as they can become invasive and overgrow the rockwork / corals.

Good for the reef tank are the macroalgae we have listed in this section
https://www.livealgae.co.uk/macroalgae/macroalgae-for-the-display-tank/

Especially beautiful macroalgae species like Gracilaria species, Ochtodes and co. 
Have a look and let us know if you have further questions. 
we are happy to help you to find the best macroalgae for your marine aquarium.

Kind regards

Manfred

Livealgae UK