921 LED's come in all types. I prefer
flat panels or
diskwith 5050 LED's. These type of lights project all the light in direction they are pointed. It will take 12 to 36 LED's to match 921 blubs. 250 to 300 Lumen for overhead lighting. Where you will find the biggest difference is in color (Kevin's).
Color Temperature is a measurement in Degrees Kelvin I find colors in the 3,000 range to yellow. Colors in the 7,000 range are to white. I prefer something in the 5,000 range.
Many supplies call there colors warm white and bright white.
You can buy a lot of cheap LED's off EBAY (where I get mine). But it will require some testing to find what suits you best. I usually find a seller that sells one bulb cheap. Order it, Takes 2-3 weeks for delivery. Then see if it works. Go back to same seller and buy enough bulbs to complete project. Most all bulbs have been less than $5 each.
There are some good US sellers that have a good record. I have not had experience with them. I will let others point you to them.