Cat5e is more than enough unless you want to future proof for 10Gb.
If that's the case then go with Cat6.
If there are very long runs you may want to consider Cat6a.
After a set distance (about 50m I believe?) Cat6 will drop off quite quickly but you would need an exceptionally big house or a really complicated long run around the building for this.
I'm about to buy some cable to wire up the upstairs and will be buying cat5e.
I can't see me buying kit that supports 10Gb at both ends for many, many, many years.