To begin with, Edinburgh has multiple physical qualities which make it particularly well-suited to fostering new businesses. It is a convenient point for commuting and travelling to meetings, equipped with trains, buses, trams, and an airport and located only an hour away from the next largest city, Glasgow.
Edinburgh contains some of the very best science parks and research centres in the whole country, meaning new technological developments, discoveries, and innovations can always be supported. In addition to these, there are large amounts of start-up premises available to allow people to get a team together and get to work.
There is also the fact that Edinburgh is a beautiful city in itself, with plenty of shopping, restaurants, entertainment and historical sites. It's the perfect place for people who have been worn out by much larger cities like London, while still being well connected.