1best 
/ˈbɛst/ adjective
superlative form of 1good or of 2well /ˈbɛst/ adjective 1 a : better than all others in quality or value
▪ You should wear your best clothes tonight. ▪ He took us to the (very) best restaurants in the city. ▪ We ate the best food and drank the best wines. ▪ You're our best customers. ▪ His modesty and sense of humor are his best qualities. ▪ Is that your best offer? ▪ I've had the best time with you! [=I've had a very enjoyable time with you] ▪ The best [=most valuable] things in life are free. ▪ Which of these do you think tastes best? ▪ Mary sends you her very best wishes/regards. ▪ He's my best friend. [=my closest/dearest friend] = He and I are best friends.
b : most skillful, talented, or successful
▪ She's the best student in her class. ▪ He won the award for best actor in a drama. ▪ the team's best player 2 : most appropriate, useful, or helpful
▪ She truly believes that this is the best way to solve the problem. ▪ She's the team's best hope/chance for a medal. ▪ She thought waiting was best. = She thought that the best thing to do was to wait. = She thought that it was best to wait. ▪ It's best to leave early if you want to be sure of arriving on time. ▪ We want to do what's best for you. ▪ He's the best man for the job. ▪ You should do whatever you think is the best thing to do. = You should do whatever you think best. ▪ We're making the best possible use of these materials.
▪ You should wear your best clothes tonight. ▪ He took us to the (very) best restaurants in the city. ▪ We ate the best food and drank the best wines. ▪ You're our best customers. ▪ His modesty and sense of humor are his best qualities. ▪ Is that your best offer? ▪ I've had the best time with you! [=I've had a very enjoyable time with you] ▪ The best [=most valuable] things in life are free. ▪ Which of these do you think tastes best? ▪ Mary sends you her very best wishes/regards. ▪ He's my best friend. [=my closest/dearest friend] = He and I are best friends.
b : most skillful, talented, or successful
▪ She's the best student in her class. ▪ He won the award for best actor in a drama. ▪ the team's best player
▪ She truly believes that this is the best way to solve the problem. ▪ She's the team's best hope/chance for a medal. ▪ She thought waiting was best. = She thought that the best thing to do was to wait. = She thought that it was best to wait. ▪ It's best to leave early if you want to be sure of arriving on time. ▪ We want to do what's best for you. ▪ He's the best man for the job. ▪ You should do whatever you think is the best thing to do. = You should do whatever you think best. ▪ We're making the best possible use of these materials.
best of all
◊The phrase best of all is often used to refer to the most important or appealing part of something that has many good parts.
▪ The machine is easy to use, easy to clean, and best of all, it's absolutely free when you order these books.
▪ The machine is easy to use, easy to clean, and best of all, it's absolutely free when you order these books.
next best
◊A person or thing that is next best is not as good as the best person or thing but is better than all others.
▪ The shortstop is the best player on the team, and the catcher is the next best player. ▪ We can't see each other often, but calling each other on the telephone is the next best thing.
▪ The shortstop is the best player on the team, and the catcher is the next best player. ▪ We can't see each other often, but calling each other on the telephone is the next best thing.
on your best behavior
◊If you are on your best behavior you are behaving very politely and well.
▪ Remember to be on your best behavior with your grandmother. ▪ The children promised to be on their best behavior.
▪ Remember to be on your best behavior with your grandmother. ▪ The children promised to be on their best behavior.
