Best components to invest in?

   Now obviously if can it's best not to skimp on any component and buy the best you can.  For PC gaming you can alos get away with not buying some of the best components and still pretty much get the best performance (and thus enjoyment) from your PC.  However, when on a budget you need to skimp somewhere.  You still can buy some 'premium' components though.  Which leads to the question: which 'premium' components should I buy and what should I skimp on?

   You could get the likes of an expensive, really good graphics card, a very good processor and an SSD, but get a cheapish case and cooler etc. (N.B. this is just a generalisation).  Yet it is these 'premium' components listed in the example above that become outdated the quickest, whilst the cheaper components listed tend to be more long term investments.  On the other hand, the former will provide you with great performance now.

  So, to the point of this post.  Do you prefer to invest in a good quality case, cooler, PSU etc. that will last you a long time and thus get you the best value for money and then get cheaper, perhaps last generation graphics etc.; or do you prefer to get a good graphics card, processor etc. and get the performance now, but have to upgrade the other components?  Do you mix and match between these vague categories and have your own priorities?*

*For those of you who can buy the best of everything; this thread isn't really for you, unless you have some advice or would just like to brag. =D