Right now, it's too late to mine bitcoin.
Other than the cheap electricity mentioned above, you can also wait until the difficulty becomes much lower if you really want to mine and make a profit out of it. The bad news is, nobody knows just how much lower it will go, or if it will ever be at all. I've seen some news talking about miners selling all of their BTC just to keep mining, but it's hard to know how much is the truth on that report since we don't see any change in difficulty yet.
Which graphic card would give good results with gpu mining ?
There are many tools that you can use to check them out. I suggest visiting the altcoin board for more details. For example, whattomine is a website that you can use to see which coin is mineable and how much profit you can earn daily if you use GPU A or B. While the cost is arguably lower, if you want to make a profit quickly, maybe you should look for other alternatives. CMIIW.