rnxrx explained the 6a and 6e, so I won't review that ground.
Regarding the new house Ethernet cabling question, I completely agree with your premise, it makes no sense to install 5e or 6 to have problems down the road, Ethernet cable ignorance is unnecessarily expensive. If I was rewiring a brand new house, I would either want one of two options:
- 6a Cabling, but only S/FTP or S/STP cables with shielded connectors. This must be installed properly, with appropriate grounding, and shielded panels and etc..
The Shielded S/FTP or S/STP 6a option would be completely appropriate, but if you for some reason wanted to really get above the curb.. you could look at 7.
Once the 7's get officially specified, I would immediately recommend them for fresh Ethernet wiring. This assumes you have IT oriented requirements, and really want to stay ahead of the curve, and everything is installed correctly. In the considerable meantime, 6a S/FTP or S/STP with fully shielded connectors would be my recommended option.