There is a big difference in quality with Deore and XT.
The XT lever at the pivot is solid, the Deore wobbles, feels cheap. Not sure if XT uses a bearing instead of a bushing like higher end SRAM brakes. Or they just use a better quality/tolerance bushing. Unsure where SLX fits in as I haven’t owned a pair. But have owned both of the others.
XT calipers are also better for the bleed nipple and banjo connection. Deore just uses a straight connection.
People make out there’s no difference other than free stroke. But it isn’t true. Even the quality of the compression hose nut boot/cover is difference. Deore is loose, XT doesn’t move. Lever play makes the deore not feel very good. The set I have are light used, would hate to see how sloppy they are after hard use.