Recommend! Lexar Professional workflow UR1 microsd card reader was used for all tests except when noted CrystalDiskMark 5.0.2 x64 was used to produce all the test results and was set up with 2 passes and 100MB read/write size All cards up to 32GB are formatted as FAT32 with 32KB allocation unit size, all 64GB cards are formatted exFAT with 128KB allocation unit size Test Results (Numbers are Sequential Read, Sequential Write, 4K Random Read, 4K Random Write in MB/s, speeds greater than 10MB/s were rounded to the whole numbers) 16 GB Alphabetically Lexar 633x** -- 88, 25, 8.7, 1.2 Panasonic U3** -- 93, 42, 11, 0.7 Sandisk Extreme Pro -- 95, 80, 7.6, 2.6 32 GB Alphabetically Delkin U3 -- 93, 59, 11, 0.6 Kingston 90R/80W -- 93, 58, 11, 0.6 Lexar 1000x -- 90, 57, 10, 1.4 Lexar 1000x with Bundled Reader* -- 148, 60, 10, 1.4 Patriot EP -- 90, 35, 10, 0.6 PNY Turbo Performance -- 91, 55, 6.9, 0.9 Samsung Pro gray -- 92, 82, 10, 3.6 Sandisk Extreme Pro -- 94, 87, 9, 3.0 Sony up to 95MB/s -- 91, 51, 4.8, 0.9 Transcend Ultimate 633x -- 93, 85, 8.1, 1.4 64 GB Alphabetically Delkin U3 -- 94, 27, 13, 0.3 Kingston 90R/80W -- 94, 25, 13, 0.3 Lexar 1000x -- 92, 56, 12, 1.5 Lexar 1000x with Bundled Reader* -- 153, 66, 11, 1.7 Patriot EP -- 81, 22, 11, 0.6 PNY Turbo Performance -- 92, 54, 6.9, 0.9 Samsung black -- 82, 20, 8.8, 2.1 Samsung Pro gray -- 90, 80, 10, 3.5 Samsung Pro+ *** -- 92, 86, 10, 5.3 <== the listed product Sandisk Extreme Plus**** -- 92, 58, 10, 2.8 Sandisk Extreme Pro - 97, 91, 10, 3.0 Sandisk Ultra ***** -- 46, 16, 7.0, 2.1 Sony up to 95MB/s -- 92, 49, 5.2, 0.9 Transcend Ultimate 633x -- 93, 83, 7.3, 1.4 128 GB Alphabetically Lexar 633x -- 78, 28, 3.3, 1.4 Sandisk Ultra -- 92, 19, 6.4, 2.4 * The Lexar 1000x card is the only UHS-II card available and tested, the bundled USB reader has extra pins for reading UHS-II card ** Came bundled with a device **** old model tested, not the current U3 model ***** old model tested Fastest Sequential Read: All tested cards were able to accomplish > 90MB/s, with the Lexar 1000x able to take advantage of UHS-II speed when using the bundled USB reader and leading the pack Fastest Sequential Write: Sandisk Extreme Pro, Samsung Pro+, Transcend Ultimate 633x Fastest Random Read: Kingston 90R/80W. Fastest Random Write: Samsung Pro+ Best overall: Samsung Pro+ and Sandisk Extreme Pro Other observations: Performance and price are not proportional when it comes to selecting a microSD card. Some of the worst performing cards in this review also happen to be the most expensive. Not all 633x cards are created equal. The two cards reviewed from Lexar and Transcend are both marked as 633x but vary in performance greatly. 4k video recording using action cams and drone cameras have a typical bitrate of 60mbps or 100mbps, corresponding to 7.5MB/s to 12.5MB/s. All cards in this review should theoretically be able to handle this usage easily. Using microsd card as supplemental phone storage potentially could benefit from a faster card, Best Looking Card (if it matters): Sandisk Extreme Pro: Red/Gold with white print Lexar 1000x: White/Gold with Black/White print Samsung Pro+: White/Black with a red stripe and Black/White print PNY Turbo: Lime Green/Black with Black/White print