In my opinion the MBP retina 15 is as close as it gets to be a perfect product. I've got the 2012 maxed out version, and still have no need for any upgrade, the 16GB RAM is still way more than necessary, the i7 still screams, and I still have more than 100GB free space.
At the time I bought it, I was looking for desktopclass performance on the go, plenty of batterylife, 15" Screen and <= 2kg to carry around. It can do all that, which is very impressive to have the paradox of light, but powerfull + powerfull but, good batterylife.
And thats where realtiy hits. If you would now want to merge these two impressive feats with repairabilty it will get thick and heavier. There is no Hattrick possible here, you can make two out of three work, but one is the sacrifice fo another.
And if you dont need any uprades in 3 years or more, than it doesnt have to be repairable, opt for Apple Care and youre good to go, and the one and only thing that needs replacement down the road, the SSD, is replaceable.