Khalsa College used to be associated with GNDU but now it is a different university. Both colleges are good and will provide you with a great experience. Some consider Khalsa to be better than GNDU, though it is a bit expensive.

GNDU has average placements. Being on the main campus won't be beneficial, as students from the regional campus also will take part with you in the placements. Hence, increasing the demand. 

Very few companies take part in the placement program and are known to offer fewer job roles. Thus, most of the time students from the main campus receive zero placements.

Both Chandigarh University and GNDU are good in their own respects. The choice varies from person to person. 

Chandigarh University:

• Many consider Chandigarh University better for its CS department. If you wish to specialize in this field, then it is a good option. It has tie-ups with reputed international company IBM, which also provides enough exposure.
• Chandigarh University CSE Placements are top-notch. It also has a well-maintained infrastructure with experienced faculty members.

GNDU:

• Some often prefer GNDU over Chandigarh University (CU). As it is a much older establishment and is a government institution, which makes the cost of studies much affordable.
• They have a highly experienced faculty.
• GNDU placements are good. Mass recruiting companies provide numerous job offers to almost all students.
• It is also known for its involvement in extracurricular activities. As this provides holistic development for the students.

If you want to join a university without having to go through any admission test, CU will be the right option, because GNDU requires students to appear for an exam prior to admission. The selection then will be based on this.