I have a Retina display
MPB and the screen is stunning. However if you are going to use it for text the odd you tube video, surfing etc, stick to the normal screen. The Retina display comes into it's own when you are dealing with images. The additional detail is outstanding, but for everyday work, stick to the standard machine.
The Retina display machines are not upgradable. The memory is hard wired onto the logic board. and I'm not sure how easy it is to upgrade the SSD.
I've run a conventional MBP for nearly 4 years now and it performs well if a bit slow ( actually more than a bit slow with 22 Mb camera files ) but then it doesn't have the 4 cores the latest machines have.
However if you take the standard 15"
MPB, add an extra 4 Gb of memory ( You have too use Apple memory at the moment as I don't think crucial have a compatible product) add a SSD and its more expensive than the equivalent Retina display model.
I would suggest that unless you have an overpowering need for a very fast machine, the conventional MPB is going to be fine for you.
If you are still in doubt, take a trip to an Apple store or dealer and decide for yourself. In the end it's the only way