This list contains different options for stock cards.
The following aims to be a general assessment that displays the facts for each valued contributor and their public Google Drives.
These are the highest quality card images available. All of these cards are available on proxycommander.com.
Chilli_Axe is the original 1200DPI+ high quality creator. He is also the creator of the great mtg-autoproxy. High card selection available, however there are a few missing. Images are 1300DPI (3288 x 4488) which is much higher than the maximum of 800DPI that MPC uses. All cards have the MTGO symbol on the front which some have critiqued as unsightly, your personal taste may vary. Contains proxy text in bottom left.
A contributor that uses Chilli_Axe's public templates and scripts to create a different set of 1300DPI cards. Like Chilli_Axe, all cards have the MTGO symbol on the front and all cards contain proxy text in bottom left.
Known for creating a great guide on how to batch remove copyright info from Scryfall Scans berndt_toast83's Google Drive has the best of both worlds when it comes to Quality and Availability. Has all cards that are present on Scryfall. The cards are all just shy of 500DPI, coming in at 497DPI. No proxy text in the bottom. All cards show the correct symbol for the series.
Other drives of interest
These drives generally have lower DPI quality but may have specific cards and alterations that the recommended drives do not have. Use low DPI images sparingly.
High card selection available, huge amount of custom art and alter cards. DPI varies wildly. Lands at 603DPI (1489 x 2080), other cards can be anywhere from 222DPI to 300DPI. Contains proxy text in bottom right.
An oldie that has been around for some years. Very high card selection available, images are around 320DPI (822 x 1116). No proxy text in the bottom. No series symbol on non-masterpiece and non-Zendikar Expedition cards. Use "Complete Sets" to find the card you're after when using the drive.