Suggestion

i have 2 domains, i checked UR,DR in ahrefs

domain.com have UR 48 and DR 46 - 5 year old - 10k backlinks (90% low quality)

domain.net have UR 17 and DR 40 - 1 year old - 1k backlinks

both are same category, i want to focus anyone, please suggest me which one is best for me

The one which you see google not penalising in the future...

I.e domain.net

Hope that helps