If you are constantly thinking about where the best place to spend your marketing budget, you might not like my answer...
My answer is... It depends.
The truth is that you are asking the wrong question.
If you are not sure where to spend your marketing dollars then you need to be asking:
Who is my ideal client? What are they thinking about? And what is going through their mind when they come across a problem that YOU can solve? AND where do they “hang out”? Instagram? Facebook? Live events? Restaurants? Television? Magazines (remember those)?
All that being said… over 500 million people are using Instagram so I would say Instagram and Facebook ads are currently the most trackable and scalable ways to promote your business.
Email is not dead either. Many consumers still engage with companies via email promotions.
Lastly, make sure everything you do/create is mobile ready.
If people don't have a good mobile experience after clicking your ad or opening your email, you've 100% wasted your marketing spend.