What are the important sacraments?

Answer 1

Eucharist, confirmation, communion, Baptism and Sacrament of the sick

Roman Catholic AnswerBy definition, all the sacraments of the Church are important, as they are all means of grace that Our Blessed Lord as left us. The most important is, of course, the Blessed Eucharist, which is the actual Body and Blood of Our Blessed Lord. All of the other Sacraments lead up to or flow from it.

from The Catechism of the Catholic Church, second edition, English translation 1994

1113 The whole liturgical life of the Church revolves around the Eucharistic sacrifice and the sacraments. (Cf. Sacrosanctum concilium 6) There are seven sacraments in the church: Baptism, Confirmation or Chrismation, Eucharist, Penance, Anointing of the Sick, Holy Orders, and Matrimony. (Cf. Council of Lyons II (1274) Denzinger-Schonmetzer, Enchiridion Symbolorum, definitionum et declarationum de rebus fidei et morum {1965} 860).

Answer 2

The Eucharist is the most important sacrament. This is the clear teaching of the Catholic Church, as is found, for example, in the Catechism of the Catholic Church:

1324 The Eucharist is "the source and summit of the Christian life" (Lumen Gentium, no. 11). "The other sacraments, and indeed all ecclesiastical ministries and works of the apostolate, are bound up with the Eucharist and are oriented toward it. For in the blessed Eucharist is contained the whole spiritual good of the Church, namely Christ himself, our Pasch" (Presbyterorum ordinis, no. 5).