僕 is a softer, typically male first-person pronoun, while 自分 in this sense can sound more formal or stiff, as often heard in military or sports contexts.
自分 is the everyday, neutral word for 'oneself', whereas 己 is a poetic or literary term for 'self' used in elevated or reflective speech.
自分 is the common modern word for "oneself" in reflexive contexts, while 我 in this sense appears mainly in fixed expressions like 我を忘れる.
自分 is the everyday, neutral word for 'oneself', while 一身 is a formal, literary term emphasizing the whole of one's person or being.
自分 is the everyday, neutral word for 'oneself', while 自ら is more formal and stresses personal initiative or direct involvement.
我が is a pre-noun adjective meaning 'my/our own' with emotional weight, while 自分 is a reflexive noun meaning 'oneself' used more neutrally as 自分の to show possession.
其 could archaically mean 'oneself', a sense now expressed by 自分 in modern Japanese.
自分 is the plain, everyday reflexive pronoun, while 自分自身 doubles up on 自分 to add emphasis like 'one's own self'.
自分 is the common reflexive pronoun for 'oneself', whereas 身 conveys the same idea in more formal or set expressions like 身の上 or 身を立てる.
自分 is a gender-neutral, somewhat formal way to say 'I' often heard in business or military speech, whereas 俺 is casual and exclusively male.
自分 can be used informally to mean 'I' or 'myself', while 私（わたくし）is the polite, formal way to refer to oneself.
