Of course, you are only eligible for a single passport, so the question may be paraphrased into: Which citizenship is the most practical to have in terms of avoiding border hassles?
Some people have dual citizenships and some may have no valid travel document at all. Nonetheless, there is a difference between holders of passports when it comes to visa regulations. I once wrote an article about my passport stamps, stating that my Norwegian passport has always been one of the best passports to hold. Flashing the red-covered booklet has been a door-opener virtually everywhere I have been.
Now, a mapped infographic produced by the magazine Good.is reveals that Norway is not on top, but very near.
This image links to the story called “How Powerful is your Passport” at Good.is. Click it to launch and zoom in on the original.
People from Finland, Sweden and the United Kingdom are granted visa-free access (or receive a visa upon arrival) to 173 countries. I will easily get into 170 countries. If you hold an American (US) passport, 172 countries will open their fences for you without much bureaucracy.
The least welcome citizens are from Eritrea, Pakistan, Somalia, Iraq and, at the bottom, Afghanistan. If you are an Afghan, only 28 countries will let you in without a visa.
The coloured map shows that we live in a biased world. The darkest colours are the “best”, and they correspond to the rich Western democracies and a few others.