There is no major difference between the two sizes of burettes besides the difference in capacity. We recommend the 25mL burette if you will be doing multiple tests in a row as the larger capacity allows you to run multiple tests without having to refill the burette with Titrant. The 10mL burette is slightly more accurate as the gradations on the burette are finer so you can read it to one additional decimal point.
The most popular is the 25mL burette although the 10mL is also a good option too. It is just whichever you prefer.
If you think you may want to do the ABV Assay or the RRS Assay in the future you may want to purchase your Pro Kit or Deluxe Lab Kit with the 10mL burette as those two assays require the 10mL burette in order to get accurate results. Or you can simply purchase an individual 10mL burette at a later time.