Essentially there are 2 types of Christian crosses; the crucifix and the cross without a corpus (body). This difference came with the reformation and the desire for the new protesting Christians to differentiate themselves from Roman Catholics.
Regardless of this major difference, after handcrafting hundreds of designs of Christian crosses, Christian bracelets, Christian earrings, and Christian earrings, and Christian rings, my position on the question of the "right look" is that there is no "right look".
As to materials, I use silver, gold, wood, stone, candles, leather brass, and copper anything goes.
Whatever cross or cross-themed item that helps you walk stronger in your faith, is the right one for you.