It's better to be honesty.刚搜的在线牛津翻译不知道是不是sinceresincere
/ sIn5sIE(r); sIn`sIr/ adj 1 (of feelings or behaviour) not pretended; genuine （指感情或行为）真实的, 诚挚的: sincere friendship, affection, dislike, disagreement, etc 诚挚的友谊、 真诚的爱、 真正的厌恶、 实质的分歧 * It is my sincere belief that... 我确信... * His was a sincere offer of help. 他真心实意愿意协助. 2 (of people) only saying things one really means or believes; straightforward （指人）诚实的, 直率的: a sincere Christian 虔诚的基督教徒 * She wasn't entirely sincere when she said she liked me. 她说她喜欢我, 这话有些言不由衷.
honestyhonesty
/ 5CnEstI; `BnEstI/ n [U] 1 quality of being honest; truthfulness 诚实; 老实; 正直; 实在. 2 plant with purple flowers and flat round semi-transparent seed-pods 缎花属植物（开紫花, 有扁圆形半透明的种子荚）. 3 (idm 习语) in all `honesty honestly 诚实地; 实在地: I can't in all honesty (ie if I must be honest) deny it. 我确实不能否认这一点.
sincere honesty的侧重点不同 前者侧重诚挚 后者侧重诚实有些不词的意思看起来相同，但是会有细微差别，最好翻翻权威性的词典 看看英文的解释，以前我的高中老师就是这样教我们的。如果有语境最好结合一下上下文。如果侧重诚挚的话，我觉得1、 4都可以，4好像有点虚拟语气表示主观愿望和强烈的感情的意味。