As someone discerning religious life, I think I would be remiss to fail to mention that St. Alphonsus Liguori (doctor of the Church and founder of a religious order) is very clear when he teaches that it would be better for an individual to stay in the world than to join a religous order that has relaxed its observances.
The call to religious life is a call to total immolation through the observance of the evangelical counsels of Christ. Whether one is called to a purely contemplative order or an apostolic/mixed order, it is absolutely essential for one to enter a community where they will be able to totally immolate theirselves for Christ.
The following list is not exhaustive and is in no way a claim that there are not other great male religious communities in the United States. However, it is a list of various orders that I have come across through research that seem to be observant (since I have not visited most of them, one would actually have to visit to investigate how observant the community is)Benedictine
Our Lady of the Annunciation of Clear Creek - Hulbert, OK - http://www.clearcreekmonks.org/Cistercian
Our Lady of Spring Bank - Sparta, WI - www.monksonline.orgCarmelite
Carmel of the Immaculate Heart of Mary - Cody, WY - http://www.carmelitemonks.org/
Hermits of the Most Blessed Virgin Mary of Mount Carmel - Lake Elmo, MN - http://www.decorcarmeli.com/Hermits.htmFranciscan
Franciscan Friars of the Immaculate - http://marymediatrix.com/
Franciscan Friars of the Renewal - http://www.franciscanfriars.com/
Franciscans of Pimitive Observance - http://romancatholicvocations.blogspot. ... vance.htmlEastern Catholic
Maronite Monks of Adoration - Petersham, MA - http://www.maronitemonks.org/Other Contemplative Orders
Camaldolese Hermits of MonteCorona - http://www.camaldolese.org/
Carthusian Charterhouse of the Transfiguration - http://transfiguration.chartreux.org/Other Apostolic Orders
Canons Regular of St. John Cantius - http://www.canons-regular.org/
Canons Regular of the New Jerusalem - http://www.canonsregular.com/
There are also religious institutes of apolstolic life that are really good like the FSSP and Institute of Christ the King. Also, alot of oratories housed by the Oratory Fathers are quire good. The one in Pittsburgh that I have a relationship with is excellent. I think the one is Toronto is supposed to be good as well.