well I haven't painted in years (3 year art school drop out) but the best medium of the two hands down is oils. What many think are disadvantages are actually advantages, for example the priming the canvass, allows you complete control over the texture of the canvass, slow dry times allows you greater freedom to adjust your composition or fix any errors (in composition or color) that you don't like (I was/am a perfectionist).
The oils last much longer time wise too, acrylics will fade and chip in the time that oils fully dry (80-100 years depending on how thick you apply them). And as far as making something that will last, oils are much easier to repair in the distant future when you're long gone.
With oils you can also get rid of all traces of your brush strokes. Once its dry to the touch you can simply sand the surface smooth. A technique largely lost since the impressionists jumped into the scene. The great masters did this as did Dali, though they did it between every layer of paint.
Also depending on how mix the oil, paint, and turpentine (which can in a pinch replace linseed oil) you mix you can achieve levels of transparency that are hard to do with acrylics alone (though not impossible).
Also oils can be framed without glass. The end result is strong enough to go unprotected (though I wouldn't ever display any painting in direct sun light.
Honestly I never liked acrylics. The only real advantage that I ever saw is that you can paint on paper with them, they're cheap, and for smaller assignments/class exercises they dried fast for making deadlines. Which for a poor art student was often the deciding factors.
But really I don't think oils are really that much more expensive if you're going for quality paint. Because they take longer to dry you need only put a piece of wax paper over your pallet and they'll be ready for you next painting session (just add a little oil and you're good to go---I use to work on 4 or 5 paintings at time let a few sit for sometimes months on end, each one had it's own pallet so I didn't have to remember how to mix certian hues) where as with acrylics you lose a lot to cleaning up between sessions. Not to mention that you also lose all the color mixing that you've done between sessions with acrylics as well.
Hope this helps....
Though on these boards I'm amazed that no brought up egg temperas (the standard before the advent of oils). Yolks are used as the medium to hold the pigment....You gotta love this medium to do it though, because you have to make your paints from scratch (pun intended).