Ethernet cable? What kind?

I want to run some Ethernet cables under the house and out to my shop so I can have interference free signal to run my apple tvs that are hooked up to stereos in the kitchen, bedroom and shop. Sometimes the signal is scratchy or drops out when the microwave is running. I was going to order some Ethernet cable but not sure what kind to get? If there is a future advantage to running cat6 or if cat5 is the way to go an will be sufficient?
For that small a cable run, the difference in price between Cat5 and Cat6 is negligible. No reason not to run Cat6. Cat6 will handle 10 Gigabit ethernet and, therefore, is more "future proof."
The options are cat 5, cat 5e, cat 6, and cat 6a.

The sweet spot is cat 6, rated for gigabit ethernet at least. Cat 6a is rated for 10 Gbps, although cat 6 might also be able to do it, but not guaranteed. Cat 6a is MUCH more expensive than cat 6.

Bottom line, get cat 6.

I assumed that your scratchy connection is wireless. If not, and you already have ethernet wires running that have a lot of noise, then consider shielded cable or cat 6a, or run them in a metal conduit.

You only need Cat6a to maintain 10gb/s for runs over 120 feet. Not worth it for most houses.
You might consider Belden's bonded pair cable especially if you'll be making any tight bends.