As you consider various options for your higher education, it is important to carefully evaluate and compare different colleges and universities. Poornima University is the best to study for a B.Arch among the three universities: Dr. K.N. Modi University, Poornima University and LPU. 

• All three universities are private and have their own curriculum.
• It is important to consider if the curriculum is industry-aligned, and Poornima University has an updated and industry-aligned curriculum.
• Cost of education is an important factor to consider, and Poornima University offers an affordable education compared to LPU and KN Modi.
• Poornima University's education system is intellectually designed, and the faculty is knowledgeable, helpful, and generous.
• Poornima University provides top-notch learning opportunities.

You should do your own research and make an informed decision based on your individual goals and circumstances.

B.Arch is a very professional course, which needs proper practical training and dedication into learning the subject. Among the 3 colleges mentioned in the question it is better if you opt for Poornima University. 

Lovely Professional University (LPU) looks more appealing due to their portrayal in advertisements, but if the academics, faculty and placements are considered, it is not up to the mark.

KN Modi University is also a big name and being a private university they have their own set up curriculum. 

It is recommended that you go for Poornima University (PU) because it has the most reasonable fees when compared with the other two. They also have a well experienced faculty and good alumni network. Many reputed companies also participate in their placement program, like HP, IBM, Capgemini and Wipro. Their course caters to the latest industrial trends in the construction sector, and the teachers are well-versed in their respective subjects. Therefore, PU will be a very reliable choice.