Hey
The courses should be choosen according to the choice of particular student. Both courses are good in their own ways. Both have different lines and different opportunities in different fields so simply we can not compare them together. But as you said you are in diploma so i would suggest you to go for Engineering instead of B.Sc because after diploma engineering is Also of 3 years and you have a better knowledge of this field now. So Engineering is best for you. But i would repeat it again it should be your choice in which field you want to go.
Hope this information is reliable for you. Best of luck.
Thank you.
Regards
Vikash Pal Jadaun