Hello dear aspirant.
Both the universities have a good reputation in the field of engineering but on an overall comparison,  Amrita university has better placement than Presidency university and it also has a good supportive faculty with a pretty good atmosphere.

Hope I am clear

Presidency University :  Placements :The placement cell of this  college is very good. Right from the first year you are prepared for good placements. You  have 2 internships. One is during 2nd year and the next one is during 4th year. Lots of companies visit this  college for placements. As this year was the first batch to pass out, the average salary package offered was around 4-5 LPA. I am sure it will increase a lot in the coming years. This university is one of the best emerging University.
Amrita University : Placements :The placements are quite good in this college and this year people placed with an average of 8 Lacs per annum. One placed with the pack of 24.5 Lacs this year and it is the highest. And the best part is 90 percent of the people have been placed every year.

Infrastructure :Of course Wi-Fi is available with priority level. Labs are also good especially the computer lab contains approximately 250 systems. Classroom is quite small when compared to other colleges.