Which side??

I lived in KL because it was very convenient being fairly close to the international airport and having all the things you will find in a big city, lots of shopping malls, restaurants, sites to see etc. I could probably have chosen Penang too, but I like living in cities. It's good because from KL I would drive to Melaka, Port Dickson, Genting, Fraser Hill, Cameron Highlands and even Penang.

The main reason I didn't choose the east coast is because I would find it too quiet. However, it is nice to drive to the east coast from KL. As for Mersing, it is too isolated for me. I visited there a long time ago on a motorbike when I lived in Singapore, and unless you want a really quiet isolated life then I wouldn't choose to live there.

So these are the quiet areas of Malaysia?
So what are the most  idealistic areas along the East coast?
Pros n cons of each part?

I think none of them, that's why I chose to live on the west coast. But they are nice to visit for holidays if you want to drive or if you don't want to visit some of the amazing places found around Asia or also for living if you want to live on a shoestring.