[ray_223]

Tough question ... not much information to go on ...

BUT ...

If you don't like the work in the business you want to start then it's unlikely you will succeed.

and

If no one is interested in paying for your product or service it's unlikely you will succeed.

So I guess it's best to choose something where a demand exists and it's something that you at least have a reasonable amount of interest in.

I'd also suggest getting your product or service in front of paying customers as quick as possible. The best way to determine if an idea will work is to try and sell it. The feedback you get from trying to sell it will direct your future (if that means to ditch your idea, change it or add to it).