Which is better, personal confession or short message confession?

If you are good at oral expression, say it orally. If you are shy and it is appropriate to express yourself in writing, then use text messages.

Confession can know each other's inner thoughts on the spot according to their expressions and actions, and you can know his attitude very early;

Short message confession, if the other party gives you a clear attitude, is ok. If he doesn't reply to text messages for a long time, you must wait and guess.

If he is interested in you, or he is willing to, he will be elated in either way, so the choice of way is not important.