If it is Marine engineering you are looking to pursue, then definetly go for Cusat.

For other courses, karunya is a little costlier compared to Cusat.

Both the colleges are pretty good with academics, infrastructure, campus placements etc.

In my opinion CUSAT has better placement oppurtunities.

For more info visit the following links:

1. https://www.careers360.com/university/cochin-university-of-science-and-technology-kochi
2. https://www.careers360.com/university/karunya-institute-of-technology-and-sciences-coimbatore