While you can choose any Statues or Thangkhas for your Chosham, there are three specific combined Statues that are generally kept in many Altars. You may choose one based on your devotion and requirement.
1. Choe Long Truel Sum
In this grouping the three statues consists of Buddha in the center, Guru Rinpoche on the right and Zhabdrung's Ngawang Namgyal on the left. For Tibetan Zhabdrung's statue is replaced by Avalokiteshvara (Chenrizig). Bhutanese consider Zhabdrung as manifestation of Avalokiteshvara.
The Buddha protects the house from fire and water disasters. Guru Rinpoche removes all type of obstacles that causes sufferings. Zhabdrung bestow the kingdom with continuous blessing and maintain its sovereignty.
2. Rigsum Goenpo
Manjushri (Jampelyang) is placed on the right, Vajrapani (Chana Dorji) on the left and Avalokiteshvara (Chenrizig) in the center.
Rigsum Goenpo protects the house and its occupants from all evils specially the ones casted upon you by others to destroy you.
3. Tse Lha Nam Sum.
A set of three statues consists of Buddha Amitayus (Sangay Tsepamey) in the center, Vijaya (Namgyelm) on the left and and White Tara (Dolkar) on the right.
Tse Lha Nam Sum does bless us with long life and good luck. Any pets and domestic animals connected with the house will also be equally blessed. It also prolongs the life of the devotees.
Along with above statues, you can also include deity based on your Birth Year Mewa as under:
5 Buddha Shakyamuni
6 Guru Rinpoche
7 Green Tara
8 Buddha Shakyamuni
9 Manjushri (Jampelyang)
By the way, you can also keep all three sets, pray and maximize maximum blessings to you, your family and all sentient beings.