What domain TLD's are safe to start a business on?

Honestly, for almost all businesses, stick with .com -- anything else is just creating unnecessary friction for users and risk for the business.

There are some exceptions:

Most national TLDs are widely accepted (so, minimal friction) in their own country. If you've got time and money enough, buy a bunch of your likely markets, and just use them to redirect to your .com.

.io has decent traction for gaming. If you can work it into your marketing enough that ~no-one accidentally uses your-company.com instead, it can work.

Depending on the business, some other TLDs might make sense, but this is when you need to look into who is running them, how widely they're supported, and make your risk assessment.

I think it's shorter the list of TLDs people might actually appreciate.

com/(net)/org are clearly the dominant trio.

National TLDs in countries with a culture of using them: co.uk, .de, .se, etc

National TLDs which have been rebranded and in some places are 'cool':

io - popular with startups/tech

vc - popular with finance/money

co - for people who can't afford an 'M'

ai - for AI

gg - popular with gaming

sh - popular with hackers

New gTLDs, these mostly haven't gotten any traction.

xyz - One of the hotter ones at the moment seems to be xyz. Alphabet (Google) is using it. Would you believe it if I told you there's been 5m in sales compared to .net's 3.4m sales in the past year?

Source: work for NameBio.com which has the largest domain sales database.

I have a nice 3 letter .co domain that people mistake with a similar .com of a large insurance company in the US. Constantly get emails from their departments and customers. I had to setup an automated reply to let them know.

The safe ones are .com, .org, .net, and your country/union's ccTLD(s) (e.g., .de and .eu if your business is in Germany, or .kr and .xn--3e0b707e if it's in South Korea).