All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad, sallallaahu ‘alayhi wa sallam, is His slave and Messenger.
First of all, you should know that all these sins are grave major sins but there is a difference between them. For instance the crime of murder is more serious than the crime of Zina (fornication and adultery) and rape, Riba (interest and/or usury) is more serious than Zina, and lying is more serious than theft.
As regards who is better, a Muslim who commits Zina after several years of practising religion and then repents, or a person who is a new Muslim; then the best amongst them is the most fearful of Allaah. Allaah Says (what means): {Indeed, the most noble of you in the sight of Allaah is the most righteous of you.}[Quran 49:13]
Therefore, if the Muslim who committed this sin has sincerely repented from it and regretted having done it, and is determined not to do it again, then he should know that a person who repents from sin is like a person who has never sinned. [Ibn Maajah and Al-Albaani]
Allaah Knows best.