It is a general question and people are confused with it. 
Everyone wants quick money nowadays, so people are chasing paid ads. It is like chasing a dream without knowing the purpose of the dream. 

First I will explain to you both in brief, then you will decide yourself which is better for you.

Few benefits of paid ads

• 1. Paid ads help you to build business very fast.
• 2. Your brand name will be visible in lesser time
• 3. You can target your audiences faster.

Cons:

• 1. You might exhaust all money and get nothing
• 2. If you have any error in web page, you will waste all your money
• 3. Sometimes, problems with configuration of ads and money get exhausted.
• 4. You have to spend lots of money to build a brand name using paid ads.

SEO:

Pros:

• 1. SEO is for long term goal
• 2. You will gets its guaranteed benefit, if you work on it regularly
• 3. You have to spend lesser and gradually

Cons:

• 1. You cannot think of benefits in 1 day or 1 week
• 2. You have to understand it's tricks and tools

For any business, I always suggest, few below points

• 1. First work to stable your business
• 2. Run your business without ads for at least 6 months
• 3. Start working on SEO from day 1, even your business is not fully ready
• 4. Focus on social sites along with SEO
• 5. As a owner, you yourself involve in each and everything
• 6. Take part with IT, sales, account and other teams.
• 7. You will understand the pain of your employee and you will think better in that direction to sort the issues.

Conclusion:
In my view, if you want money immediately, go for both in parallel ie. SEO and paid ads. Paid ads will give you results in a short time but are not guaranteed. On the other hand, SEO will benefit you in the long term. 

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