A few of my friends graduated from both Karunya and Veltech University and having read a few online reviews of the alumni here are a few tips for you. 

• If you want to get a good education from a highly qualified faculty then Veltech is not a good option. 
• If you want a job in a core company after graduation and you are a non-IT or CS guy then go for Karunya University. 
• Veltech University also does not offer happening campus life. 
• It also depends on which department you wanna get admission to. Veltech is good for Mechanical engineering but if you want CSE or ECE, then choose Karunya University.

Make a calculative choice considering every parameter and choose the best for you.