Considering career scope and placement prospects, Computer Science Engineering is much better than Mechanical Engineering and you effectively have chances in ending up with good packages at Top Companies.

However, Mechanical Engineering isnt that bad. You may pursue Mechanical, if you were perhaps interested in Friction, Rotational Mechanics, Calculus, Thermodynamics and Fluid Mechanics during your JEE Preparation as these form the foundation for Mechanical Engineering. You do have a good scope in Core Mechanical Engineering during Placements, as far as Your Engineering College is a Tier 1, 2 or 3 Institute (Within NIRF 100 Rank). Otherwise, you may appear for GATE and pursue PG from Higher Technical Institutes like IITs, NITs, BITS Pilani and Top State Engineering Colleges for better career scope and placement prospects.