Three of your Options are very Comparable. If you have plans to go for a Masters or Postgraduation in future, COEP can be a very good option providing in depth Technical Education. As far as Placements are concerned, Civil Engineering at COEP has almost 70% placements.

However from Placement as well as Career aspect, I believe a degree in Mechanical Engineering will be more effective than Civil as far as career scope and prospects are concerned. SPCE Mumbai too is an excellent Technical Institutes in Maharashtra next to COEP and VJTI and has good infrastructure, faculty, research facilities and an excellent employer outlook. Being located near Industrial Hubs at Mumbai and Pune provide strong scope and impetus in training and placement prospects. Mechanical in general has more scope in both Private and Public Sector. Among PSUs, almost all Enterprises have vacancies under Mechanical Engineering annually through GATE.

For more information about SPCE Mumbai do follow the link below

https://www.careers360.com/colleges/sardar-patel-college-of-engineering-mumbai/reviews

For more information about the branch of Mechanical Engineering do follow the link below

https://www.careers360.com/courses/mechanical-engineering-course