So there are a number of options in Israel - I will try and provide a bit of background for each one. Just an aside, please note there is not such a thing as a bad yeshiva, it is always about finding the right fit for the right person.
As has been mentioned, the two most 'famous' ones are Aish and Ohr Sameach.
Founded in 1972 and situated in a beautiful complex in Maalot Dafna. The Yeshiva has over 400 full-time students and hundreds more participating in short-term programs. They have a phenomenal set of Rebbeim that are all noted speakers and warm personalities. The faculty includes Rabbi Yitzchak Breitowitz, rav of the kehilla, Rabbi Nota Schiller - rosh yeshiva, Rabbi Dovid Gottlieb, a former professor of analytical philosophy at Johns Hopkins University and Rabbi Dovid Kaplan, author of The Kiruv Files and the Impact! series. Perhaps two major pros of Yeshivas Ohr Sameach is the fact that they have a range of programmes depending on where the individual is holding from beginner courses through to Rabbinic teacher training, so the bochur in question can therefore choose the programme that best suits where he is up to and go on from there. Additionally, like Aish, Ohr Sameach is an international institution and has many programmes abroad which ensures that any returning bochur can still maintain links afterwards if necessary.
Aish was founded in 1974 by Rabbi Noach Weinberg zt"l and is situated overlooking the Kosel. The current Rosh Yeshiva is Rabbi Yitzchak Berkovits shlita who is regarded as a leading posek and one of the first ports of call when it comes to Baalei Teshuva related shailos. Like Ohr Sameach, there are a number of educational programmes available including the famous Foundations Programme which doesn’t expect any background knowledge, just a desire to learn and is thus personalised accordingly. This runs for three months. Following this, there is the Beit Midrash Program which helps to foster skills in learning Gemara as well as providing answers to a plethora of questions thereby providing them with a firm foundation for life after yeshiva. Finally, there is the Aish Gesher programme which is for those graduating high school (so possibly not relevant to your friend) with diverse backgrounds. The program offers the chance to spend a year living in the Old City of Jerusalem, studying Jewish texts at a serious level.
Based in Yerushalayim and led by Rabbi Shaya Karlinsky the Yeshiva caters for university-educated and professional men committed to spiritual and personal growth. Their website writes:
Shapell’s/Darché Noam prepares men in their 20’s and 30’s for a rich and multi-faceted Torah-centered life. Our educational programs facilitate direct encounters with classic, traditional sources, coupled with a focus on character refinement and spiritual growth, cultivating a lifetime love of Hashem, with the study and practice of His Torah. We inspire honor and appreciation of the range of Torah communities, guiding students to discover the fitting environment for them to raise their families and make their unique contribution to the Jewish people.
Situated in Har Nof, Dvar Yerushalayim was one of the first yeshivos to cater to Baalei Teshuva, opening over 45 years ago. Founded and led by Rabbi Boruch Horovitz shlita, the yeshiva offers a full spec of programmes which can be seen here. Their website writes:
For more than 40 years Dvar Yerushalayim has been servings Jews from all over the world. Our Yeshiva is one of the first Yeshivot to cater to Jewish students with limited backgrounds in Torah Learning. The Academy Designed a unique professional introduction to the source-material of Torah in order to facilitate successful study by beginning students. From the very start the Yeshiva has done pioneer work in the Teshuva movement, reaching out to thousands of young men on campuses; on kibbutzim; and on Israeli Army and Air Force bases - to restore and renew their Jewish roots. Our Rosh Yeshiva, Dean and founder of the Jerusalem Academy, Rabbi B. Horovitz, has over 50 years experience as spiritual advisor for Jewish students throughout the world. Students learning under his guidance, students have been able to relate Torah sources to modern problems, thus reshaping their lives as Torah-true Jews. Students come to the Jerusalem Academy from all over the world. Classes are conducted in English, Hebrew, French, Spanish and Russian. The Student body is composed of professionals, university graduates, and intellectually oriented young men.
Located on Mount Zion and established in 1967 by Rabbi Mordechai Goldstein zt"l, it has grown to include a multitude of programs for men and women of all levels of Jewish knowledge and garnered fame with the creation of the Diaspora Yeshiva Band. The website writes:
The goal of the Diaspora Yeshiva is to make Gedolim - outstanding Torah personalities who are dedicated scholars and leaders capable of actualizing Torah values in this modern world. If you are seriously interested in finding out the meaning of in-depth Torah study, coming close to G-d, and developing your Jewish potential to the utmost, Diaspora Yeshiva has a place for you. The Yeshiva offers a total program of traditional Jewish study, in a highly charged atmosphere of vibrancy and growth.
A Special Study of Character and Personality Development (Mussar)In keeping with the goal of maintaining the highest levels of scholarship and understanding, the Yeshiva employs a highly specialized handed-down method of learning. The wonderful depths of Torah wisdom are revealed to the student through an exciting question and answer format in which he is stimulated to search for real truth and be responsible for his conclusions. The most important aspect of this method is the crystallization of learning formulas, which the student himself can reproduce, in an independent study.
Yeshiva for Excellence, Truth, learning, openness, character, leadership, and warmth; this is a Yeshiva for excellence, a powerful Torah Center where you can achieve the most exalted levels available to man. If you would like to take the challenge, we would love to help you grow.