I like castor, avocado, coconut, olive...gosh there are soooo many.. I think you ll find that "best" is a relative term to each soaper and relates to personal subjective likes/dislikes like anything else
I rarely ever make a soap that doesn't have shea butter in it. Jojoba oil is nice. A higher superfat helps too... I routinely use 8%, and keeping the olive on the high side, the lions share of the oil, as it is very moisturizing . I also like castor(which gives the bubbles a little boost especially when you're using a high percentage of olive and a butter).