Which is better, SMD or DIP?
Each has their own advantage. There are some very cheap SMD diodes on the market which is why you may see low prices for LED signs. Lower cost means lower material quality so cheap SMDs are not a good option.
When you use good quality SMD, the price is similar with DIP. The benefit of SMD is that you can get higher than 10mm resolution, such as 8mm, 6mm, 3.91mm, etc. Also, the viewing angle of SMD is greater.
DIP LED screens can be brighter, often 10,000+ nits, and consume less than half the power of SMD. The highest resolution for DIP is 10mm. In the past there were 6.67mm and 8mm DIP modules but they were using DIP146 and DIP246 diodes which had no advantage against SMD. Only the DIP346 used in P10 and P16 have the brightness/power saving advantage.