While I am unfamiliar with the term ‘digital nomad,’ I am guessing that this refers to people who live on temporary tourist visas and rotate between countries while maintaining an online source of income. For this reason, often, the best types of passports for these people to hold are passports that allow you to access as many countries as possible visa-free. According to this list of the world’s most powerful passports, the top 10–33 passports are listed below:

Germany, Sweden (158 countries)
Finland, Switzerland, France, Spain, UK (157 countries)
Denmark, Italy, Netherlands, Belgium, South Korea, Norway (156 countries)
Singapore, Luxembourg, Austria, Portugal, USA (155 countries)
Greece, Ireland, Japan (154 countries)
Canada, New Zealand (153 countries)
Czech Republic, Hungary (152 countries)
Malta, Iceland, Australia (151 countries)
Malaysia, Poland (150 countries)
Slovenia, Slovakia (149 countries)
The countries I have italicized require naturalized citizens to renounce their foreign nationality before becoming citizens. This might be useful for you, particularly since you wish to avoid paying US taxes.

However, all of the countries listed above require at least five years of legal residence to qualify for naturalization, and many also expect you to have a certain level of knowledge in the local/national language before being able to naturalize.

Digital nomads would probably seek passports that allow for freedom of movement in selected regions of the world, such as the EU - luckily, all EU passports feature within the top 20 most potent world passports.