When you bought iPhone 6 how much memory was readily available for you?

This would depend on which size memory you chose in the first place: 16, 64, or 128GB.

Then the iOS and the pre-installed apps take up memory, so there will be about 8–10GB less than what is listed.

From Apple’s Knowledge Base: ”The storage media in your Apple product, like all storage devices, uses some of its capacity for formatting, so actual capacity available for applications and files will be less. In addition, other factors, such as pre-installed systems or other software and media, will also use part of the available storage capacity.”

Yes that’s exactly what I was wondering about. I noticed they dont have a 32gb option

The 16GB has historically been the best seller, because of the lower price, so I guess they didn’t want to eliminate the entry-level; but for people with a bit extra to spend, most will go for the larger capacity models. I wasn’t able to find an official explanation, though.

It shouldn’t vary from the 5S numbers Ars listed.

Device Space available (iOS 7.1.2) Space available (iOS 8.0 GM)
32GB iPhone 4S (AT&T) 27.4GB 26.6GB
32GB iPhone 5 (VZW) 27.3GB 26.7GB
32GB iPhone 5C (AT&T) 27.2GB 26.5GB
64GB iPhone 5S (AT&T) 56.0GB 55.1GB
32GB iPod Touch 5 27.3GB 26.6GB
16GB iPad Mini (Wi-Fi) 13.0GB 12.1GB
32GB iPad 4 (Wi-Fi) 27.0GB 26.1GB
16GB Retina iPad Mini (Wi-Fi) 12.3GB 11.0GB