These are totally different terms you want to compare. SEO is the process of increasing the organic visibility of the web pages on the SERP results by performing On-Page and Off-Page activities. SMM is like PPC but for the Social Media platforms. SMM help to reach your desired customers to you and also helpt to increase your Brand Awareness or help in becoming a Brand.
Both strategies should be considered. But honestly, it depends on which your business is related to. SEO is more for google rankings. Social media is for attracting more audience to your website. They are both effective.
It really does depend on how fast he wants to move, as SEO is certainly ongoing long-term process, however, if you are looking for instant gratification success/fail, then your best b would be to go with PPC, even then, with PPC, you still need to have a skill, otherwise, you can run ads, and your money will slip through your fingers with nothing to show for, and this can easily happen with SEO also, and you should already have researched your niche with a fine comb before using PPC or SEO, or you will just simply bleed cash into thin air.
SMM can bring not only law quality traff. For example Instagram is able to provide target audience fast, and it can by quality.
SEO itself a website promoting activity. it is the vital factor of digital marketing. While SMM is to create brand awareness, creating a brand name, connect to your audience, this can be done by boosting your boost, join the niche group.
If you want to market your website or service to target a specific audience, SMM is the way to go. For example, if you a providing a service that will attract the younger generation, then SMM should -in theory- be more effective than SEO. Decide on what you want exactly then based on that, choose what will be more suitable for you.
I recommend you to try both marketing channels because for a business can work and for another not so good. You can try work with an agency and find what is the best marketing channel for your business. Check this agencies: Redantler Promos Magnite
I think both are vitally important. You have to be just as accessible on social media as you are on the general Web. For example, think of everyone who has an Android phone - these folks still use the search bar that usually appears by default on their home screens to search for content. So even in the mobile/social era, search marketing/seo is still vitally important. But at the same time, so is social media marketing. Facebook has well over 1 billion users, though of course there is question as to just how many are actually active. The inactivity question notwithstanding, however, we can surmise that several hundred million people actively use Facebook on a daily basis. And while Facebook is the "gold standard" in social media, the same can be said for other networks like Twitter and even Instagram (which is owned by Facebook). Therefore, it is important to appear here, as well. In my own businesses, I look at it this way: SMM = brand building SEO = producing sales
The SEO and SEM are the entirely different strategies and you have to decide which one best suits you depending on your requirements.
Its a very personal thing but a they both go hand in hand, SEO is all about your presence on the search engine where SMM reflects your presence on the social media so its better. A person who views you on social media would also want to check your website out or search you on a search engine and if SEO is done right you brand will create a better impact on a user hence increasing your sales. Your activity anywhere on the internet shows how aware you are to your surrounding and its builds a lot of trust in your audience.