In my experience, which has been with a HR based product, LinkedIn Ads are much much better than google or facebook ads. They get better quality click through rates and are more accurate as far as who they show the ads to. They are also cheaper and way easy to operate. Further, they are aimed at someone doing A B testing with ads so they have an easy platform for that which makes it easy to track the different kinds of ads, disable the ones that aren't working and move your funds toward the ones that are working.
I would definitely recommend LinkedIn ads for testing an MVP and monitoring AB testing ads as well as for more established businesses. However, for more established businesses, I would suggest you run a week or with your target audience and see how it goes. If it doesnt, switch up the audience, etc. So, whether it's a start-up or a more mature business, make sure to test your strategy on there at first, and then when you got it, let it go and gain clients, monitoring regurarly.
Hope that helps,