Looking at the responses, I think most of the ppl here are either college guys or freshers. Let me share my experience then:
I am in private sector, having >5 years of experience now (currently working for American Express). Initially I wanted to move to govt. sector as I wasn't getting much at that time. Now, when I see myself and my fellow childhood friends who are in govt. sector, I always thank to god that he didn't get me in govt.
Points being:
1) Private sector has no barriers. You can move to any direction, learn & work on things you want (atleast in IT sector). In 5 years, I've switched couple of times as I simply didn't like what I was doing, and now I think I am at the right place. You cannot do such thing (atleast easily) in govt. sector.
2) Exposure: the quality of workplace, guest houses, talented leaders, classy & modern people, cute, hot and stylish ladies

...govt. sector don't even have such things, let alone the comparison. The company of smart people grooms you inside out, redefines your lifestyle..makes you better. If you are working for a good MNC: outings to high class properties, wild parties is plus. Believe me, I have friends who are in very good govt. jobs. I've been to their parties, seen their colleagues etc. they are nothing when compared to Private.
Also, dont forget foreign/onsite trips.
3) Money: when i started, I was earning very less and so my mind was not fixed. But in private, you can grow exponentially, monetary wise. I've already surpassed almost all of my fellow buddies working in govt. sector, even with a huge margin from most of them. Today by god's grace, I have everything I used to think about in my childhood. If I need something, I can buy without thinking even twice.
4) Facilities: Yes, govt. sector provides you discounted fares, ration etc., home, tax exemptions etc. But when you earn good, you won't even bother about these things. Govt. provide all those things simply because it pays less.
5) the only thing which I see in govt. job is that its impactful, if required. You have any formal trouble, have some work to be done in govt. office, your govt. designation (may) aid you. But thankfully, I have some good contacts which sometimes help me out. lol.
Well, the choice depends from person to person. Some wants to just go to office, spend some time there and come back home. So, they look for govt. sector because it has job security. Some really want to help their nation/or looks for core stream of their interest (mechanical/chemical etc,), gets into core govt. divison and works really hard.
I've also seen people in private, doing nothing, getting annual hikes, working on same level for years. So they also dont get much growth but they are still happy. Point is, you will find both kind of situations in either of the sectors.
For me, Private.