Chanting and mantras are a form of meditation, especially when the chant is simple.
I personally prefer chanting because I just can't let my breath go if I'm focusing on it - control always takes over because I spent decades working various breath control techniques.
All forms of Buddhism use long, medium, and short chants.
The benefits of chanting is that you focus on the meaning of the words first, which acts like a visualization activity in sports of bringing out those qualities in yourself.
Then eventually with practice there's just the words, and then when the words drop off, the realizations come.
The long chants get much longer than the ones I'm going to list, so I'll list the ones that can be typically used for daily practice.
What I'm calling "medium" chants are typically dharanis that are loosely defined as "a bit lengthier than standard mantras."
Short chants or mantras have no preset length, but I've read that the longer the mantra, the more repetition it needs. So I tend to ball park it around 10 syllables (longer ones like Medicine Buddha short mantra have a lot of repetition).
In Theravada the long chant would be something like the morning service or the metta chant (you can find chanting guides on buddhanet.net for a taste).
An example of a medium (dharani) length chant in Theravada would be the Iti Pi So chant:
http://www.accesstoinsight.org/lib/authors/dhammayut/chanting.html wrote:Itipi so bhagavā arahaṃ sammā-sambuddho,
He is a Blessed One, a Worthy One, a Rightly Self-awakened One,
Vijjā-caraṇa-sampanno sugato lokavidū,
consummate in knowledge & conduct, one who has gone the good way, knower of the cosmos,
Anuttaro purisa-damma-sārathi satthā deva-manussānaṃ buddho bhagavāti.
unexcelled trainer of those who can be taught, teacher of human & divine beings; awakened; blessed.
The short chant, or mantra, is "Buddho", which means "awakening" or "enlightenment".
I like the following quote on this:
http://www.accesstoinsight.org/lib/thai/dune/giftsheleft.html wrote:"Have the mind give rise to a single preoccupation. Don't send it outside. Let the mind stay right in the mind. Let the mind meditate on its own. Let it be the one that keeps repeating buddho, buddho. And then genuine buddho will appear in the mind. You'll know for yourself what buddho is like. That's all there is to it. There's not a whole lot..."
In many Mahayana schools (it's not really 1 school), the longer chants typically include the Heart Sutra, the Diamond Sutra, or the Great Compassion Mantra (it's called "mantra" and "dharani", but it's pretty long), you may have some experience with these.
A typical example of a medium/dharani chant in Mahayana would be the Medicine Buddha dharani (which you may be familiar with):
http://en.wikipedia.org/wiki/Bhaisajyaguru wrote:namo bhagavate bhaiṣajyaguru
Honor to the Blessed One, Medicine Guru
Lapis Lazuli Radiance Tathagata
arhate samyaksambuddhāya tadyathā:
a Worthy One, a Rightly Self-awakened One, it is said:
oṃ bhaiṣajye bhaiṣajye mahābhaiṣajya-samudgate svāhā.
Suffering, suffering, Great Medicine hail!
The short/mantra Medicine Buddha chant is that last line.
In many Mahayana schools, people chant the short mantra of Amitabha Buddha:
http://en.wikipedia.org/wiki/Amitabha wrote:Sanskrit: अमिताभ Amitābha, Amitāyus
Chinese: 阿彌陀佛(T) / 阿弥陀佛(S)
**Pinyin: Āmítuó Fó
**Wade-Giles: A-mi-t’uo Fo
Japanese: 阿弥陀仏 Amida Butsu
Korean: 아미타불 A-mi-ta Bul
Mongolian: Цаглашгүй гэрэлт
**Tsaglasi ügei gereltu
**od dpag med
Vietnamese: A-di-đà Phật
One thing to note with all this stuff is that it's practice. It's not like a belief in God, where if you don't believe, you're going to he||. You're not praying to a God to come and make you Enlightened or to do things for you. You're practicing. You have to do your own work. Focusing on these examples will bring out changes in yourself. Even Pure Land, which gets bashed for being some sort of God worship, you still have to do the work. Even the most staunch of the "Other Power" Pure Land schools would never tell you not to recite Namo Amida Butsu. If you don't hit Enlightenment this lifetime, you still recite at the time of death to calm your mind, find the Pure Land, and go calmly. How peacefully you go usually depends on the amount of time and effort you put into practice & ethics during your life.
With tulkus, it's my understanding that a healthy doubt with regards to the tulku system is not a bad thing. If you're not sold on rebirth, that's fine. If you're open to the idea, they can actually be a lesson in anatta, anicca, dukkha - tulkus don't typically pop out of the womb enlightened, even if their prior birth was supposed to have had great attainments, they don't have the same personality though they may have many of the same propensities. Not the same, not completely different.