There is no point in having a social media presence if it is not regularly updated and used. So the best ones are the ones you have time for. As you can see from the attached chart each platform has its own target audience, how people interact with the platform and what they go there to do and find. 
In order to have a good social media presence you need to be uploading relevant and regular content. For you, regular might be every day or once a week. Your followers will come to learn what your patterns are for interacting with them. As long as this activity is relatively consistent you will keep them engaged. 
People interact with content they relate to. Whilst beautiful imagery professionally taken with filters and back drops does have a place on social media, for the most part people like to see unfiltered, no fuss, relatable content. 
We now live in an overly communicative society - so the good, bad and the ugly are all aspects people want to see. 
Make the uploading of content part of your business practices. For instance, if you owned a hairdressing salon you wouldn't leave for the day without sweeping the floor. 
Uploading and interacting with social media is no different. Make it a part of your everyday routine. Interacting on socials isn't only about uploading your own content you can be present by sharing others content, liking or commenting on others pages also. 
The key to getting started on social media is not to over think things too much. 

WHICH SOCIAL MEDIA PLATFORM? (comparison chart)
It's the one you have time for.
Chart summary: Who are the main users of this platform? What content can I expect to see? Why should I put my content on this platform? Tell me the good things about this platform? What are the downfalls of this platform?
Facebook: 25-45 year olds, Boomers; Live feeds, photos & information; Relationship building, targeted local advertising; Likely the platform most people are familiar with; FB doesn't have the organic reach a lot of the others have.
Instagram: 18-25 year olds, Millennials; Inspiration, polls & questions, less written content; Influences are plenty, Ecommerce, more organic reach; Less text which can make for quicker posting; Paid advertising is expensive.
Snapchat: 13-24 year olds, Teens; Trends, feel good content, challenges; Video advertising; "on trend" things are picked up very quickly here; Lacking relationship building.
LinkedIn: 35-55 year olds, Professional; Long content; Business to business, organic reach; In-depth reports, targeted audience; Perhaps a too small too customised audience.
TikTok: 10-24 year olds; Entertainment, trends, challenges; Influencer, series content; "on trend" things are picked up very quickly here; Lacking relationship building.
Twitter: 25-65year olds, educated, financially secure; News/politics, discussions/debates, humour; Customer service based offerings; Very direct targeted information; Not many advertising opportunities.