應該是：all of them.

這要看情況而定。如果是一個簡單句用前者，如果是一個定語從句就用後面一個。

all of which作定語,而and後不跟定語,all of them可作主賓表

一般用於定語從句中，在定語從句中有區別

all of them 可以作為主語，指所有的XXX，這個them所指的物件前文中已經提到的，可以指人、事物等等，舉個簡單的例子：We have ten people in the room; all of them are girls. 其中all of them are girls也可單獨成句。

all of which和all of whom 都只能引導從句,進行補充說明，不可置於句首。但which指事情或者物，whom指人。例句：

1、The vases on display are highly valuable, all of which were made in China.這句也可以拆分成兩句The vases on display are highly valuable. All of the vases(them) were made in China.

2、The students are hard-working, all of whom wish to enter top universities. 這句可拆分為The students are hard-working. All of the students(them) wish to enter top universities

all of後面既可以接名詞，也可以接代詞。

1、all是一個形容詞或代詞，而all of是個形容詞短語。

2、all可以單獨用（此時充當代詞），如 All is ok，一切都好。all of必須接詞語，如：All of the students have left.

3、當all和all of都用作形容詞“所有的...”，all後面只能接名詞，而all of後面既可以接名詞，也可以接代詞。

如：All students, all people。All of the students, all of the people。All of them，不能用all them。

擴充套件資料：

all of的近義詞：

1、altogether

英 [ˌɔːltəˈɡeðə(r)] 美 [ˌɔːltəˈɡeðər]

adv.(用以強調)完全，全部;(表示總數或總額)總共，一共;總之;總而言之。

Altogether, it was a delightful town garden, peaceful and secluded.

總體上說，這是個令人愉快的城市花園，寧靜而偏僻。

2、in all

英 [ɪn ɔːl] 美 [ɪn ɔːl]

非常;總計。

all, she has eight costume changes.

她總共換了8次演出服。