is it faster to get a smaller HDD for a boot drive, over lets say a 1TB? eg. 500GB to 1TB. or would it be quicker to get a 1TB and partition it off so the OS is installed on the outer edge where the disk spins the fastest....? and have the second Partition on the rest of the drive.
For hard drives, generally speaking bigger = faster because there's more data on each track as Mimoso says.
For SSDs, generally speaking bigger = faster because they use more flash memory chips which are internally configured like a RAID array.
But when comparing HDDs to SSDs, SSDs will ALWAYS have much, much faster access times regardless of the relative size of the HDD or SSD. Faster access times means faster booting and application startup.
HDDs may still have faster write transfer rates than an SSD (depends on the brand and model), but for the most part that doesn't affect overall performance very much.