There are multiple organisations invested in rating democracies worldwide, the main one is from The Economist EIU ,(https://www.eiu.com/n/campaigns/democracy-index-2025/, there are numerous places where the raw data is published more accessible such as here: https://ourworldindata.org/grapher/democracy-index-eiu).

I personally prefer the index made by Freedom House (https://freedomhouse.org/report/freedom-world) because it includes what a regular citizen experiences:

For each country and territory, Freedom in the World analyzes the electoral process, political pluralism and participation, the functioning of the government, freedom of expression and of belief, associational and organizational rights, the rule of law, and personal autonomy and individual rights.

Their assessment of the US democracy:

EIU (2024): 7.85/10, "flawed democracy" Freedom in the world score (2025): 81/100

These scores obviously are not about other things that matter, like economic stability or access to healthcare.