Because of the nature of your consulting business (web development) you have the advantage of being able to effectively offer your services remotely. I think more important than deciding between a large or small city, is finding a city where you would enjoy living and building a network. Is there a city where you have a critical mass of friends, family, potential business partners? Is there a city you'd simply be happier in because it fits your lifestyle, whether it's access to outdoors or city living?

Do you have a more specific market segment you'd like as your clients? Do you want to service just tech startups? Health tech startups? Larger companies? Unless you plan to really narrow down into a specific niche, like consulting just for the aerospace industry where the companies are usually found in a specific city or region, web development offers you a lot of geographic flexibility. More and more companies like Automatic or Zapier have completely remote teams and the trend towards that is only accelerating.

Choose a city where you'll be happiest and most likely to be able to participate in the lifestyle the city provides. Not only will you be more productive if you're happy, you'll have more opportunities to grow your network organically by meeting friends through your hobbies or social activities that then turn into clients.

I'd caution against being overly analytical or coldly rational when making this decision. Follow your gut. Choose a city you'd love to live in and grow a business in. I know wildly wealthy and successful entrepreneurs in cities both small and large.