The Karbonn Mach Five definitely has better connectivity to cell towers due to quad band compared to Micromax which is dual band! You will know the difference during calls and browsing the internet. Besides Karbonn offers double to storage and RAM which will be fruitful in the future.
The micromax has slightly more battery which is not significant and there is not much difference between a 13M and 8M Camera for picture quality. Also, the micromax has Octa-core processor compared to the Quad-core in Karbonn. This is also not a significant difference as Octa-core will not be utilized for low end phones which can run limited apps with just 1 GB RAM that will be a bottleneck!!
You can compare the phones in NDTV Mobile Comparison or other site like 91 mobiles too.
If you do not care for the Camera, Battery and internal storage then the Fly Snap at Rs 2500 could give the same performance at less than half the price too.
Best of Luck, Dino.