There are several advantages to becoming a U.S. citizen ("naturalizing") instead of remaining a lawful permanent resident (green card holder), but also a few disadvantages you might want to consider.
For instance, becoming a U.S. citizen means you'll never have to worry about being deported or being refused entry into the United States. What's more, you'll have an easier time helping close family members to immigrate.
Then again, you might lose citizenship in your home country, and discover you've taken on new obligations, such as serving on juries for court trials and paying U.S. taxes on your foreign income.
Your decision whether to apply to naturalize could depend on how strongly you feel about any of the advantages or disadvantages, which are further discussed below.
Advantages to Becoming a U.S. Citizen
Here is a summary of the positive things that come with naturalized U.S. citizenship.
U.S. Citizens Are Protected From Deportation
You might not plan on doing anything that could get you deported (removed) from the United States, but why take the chance? U.S. citizens cannot be deported unless their U.S. citizenship is taken away (which is very hard to do).
Naturalizing can be an especially good idea for people who committed a minor crime or did something else more than five years ago that could have gotten them deported but didn't. Whatever you did, it won't necessarily stop you from getting naturalized citizenship at this point (but consult with an attorney for a full personalized analysis of the risks and benefits). Once you have citizenship, you won't have to worry about a knock on your door from ICE (U.S. Immigration and Customs Enforcement).
U.S. Citizens Gain Voting Rights
One of the big reasons people want to naturalize is so they can vote in government elections in the United States. Until you become a U.S. citizen, other people are making decisions about issues that affect your life in important ways, and you have no say in the matter. Once you are a citizen, you can even run for elected office yourself; except for the office of president. (The U.S. president must, by law, have been born in the United States.)
U.S. Citizens Can Easily Travel to and From the United States
Returning to the United States after foreign travel becomes easier once you are a U.S. citizen. You can stay outside the country for as long as you want—even make your home in a different country for as long as you want—and always get back in. If you obtain a U.S. passport, you might even find it easier to get a visa or other form of entry into more countries as a U.S. citizen.
U.S. Citizens Have Access to Many Government Jobs and Benefits
​Certain state and federal benefits (cash or services) are available to U.S. citizens only. If you need to take advantage of those government benefit programs, it could be worthwhile to become a citizen.
Also, if you're job hunting, you'll become eligible for more federal jobs and law enforcement jobs if you become a U.S. citizen. The same is true for certain grants given out by the government—they're available only to U.S. citizens.
U.S. Citizens Can Arrange Faster Immigration of Family Members
Would you like to bring your parents, brother, sister, or a fiancé to live in the United States? You'll need to be a U.S. citizen before you can do so. It's also typically quicker and easier to bring a spouse or child to the United States if you're a citizen rather than a lawful permanent resident.
Not only that, but if you have children under 18 who have green cards, or you are planning to have children, they can get U.S. citizenship automatically through you if you are a citizen.
U.S. Citizens Need Not Deal With U.S. Immigration Agencies Anymore
Once you become a U.S. citizen, you don't have to deal with U.S. Citizenship and Immigration Services (USCIS) again, at least with regard to yourself. (Of course, you'll have to deal with USCIS again if you want to sponsor a relative or employee for U.S. permanent residence.)
This also means you don't have to pay to renew your green card every 10 years (or if you lose it). Nor do you have to notify USCIS each time you move or change your address. You also won't be legally bound to carry around proof of your immigration status (your green card) everywhere you go.
Disadvantages to Becoming a U.S. Citizen
The picture isn't entirely rosy. Here are some of the down sides of becoming a citizen of the United States.
U.S. Citizens Must Pay U.S. Taxes Even on Foreign Income
The United States imposes taxes on its citizens for income earned anywhere in the world. If you plan to earn income outside the United States, you need to speak with a tax expert to see how becoming a U.S. citizen might affect you financially.
Once you become a U.S. citizen, it's difficult to ever escape your tax liability to the U.S. government, even if you voluntarily give up your citizenship. A green card holder, on the other hand, can give up lawful U.S. residence and not have to worry about filing U.S. tax returns for more than a year after that.
So, if you're thinking that you might eventually move out of the United States (when you retire, for example) to a place with lower taxes, see whether naturalizing makes sense financially.
U.S. Citizens Must Perform Jury Duty
Unless you think you would enjoy jury duty, the possibility of being called to serve on a jury in a U.S. courtroom; which only U.S. citizens can do; can considered a disadvantage to U.S. citizenship. Many people do not like being required to spend the time and possibly lose money by not being able to work while serving on a jury for days, weeks, or even months. Then again, it's an important part of one's civic duty, and a window into the American system of justice.
Depending on Your Country, Becoming a U.S. Citizen Could Cause Your to Lose Citizenship There
The main reason people decide not to become U.S. citizens is because they don't want to give up citizenship in their country of birth or any other country where they hold citizenship. Often this is a fear that has no basis in reality, because the United States does not force you to give up other citizenships if you become a U.S. citizen, and your country of citizenship might allow you to remain a citizen of that country even if you become a U.S. citizen. (This is known as becoming a "dual citizen.")
However, there are countries that will take away your citizenship or other privileges of being from that country if you become a U.S. citizen, and that could be a big disadvantage. You need to find out whether you're going to lose rights in your native country or other countries where you hold citizenship if you become a U.S. citizen. Then decide whether you'd prefer the rights of U.S. citizenship.
Getting Legal Help
As part of your decision-making process, have a look at Who Definitely Should Hire a Lawyer When Applying for U.S. Citizenship?.