DDR 3 may be older but technically it's still better cuz that what the tech level is catered around ATM. You can get DDR 4 but you'd notice the the hole in your wallet way before noticing much of a performance difference. Plus they got DDR 6 since like 2012. Does that mean ppl hurrying to buy a $3k RAM card hell no! Hope this helps. If not YouTube ddr3 Vs 4 to help decide
I'd go DDR4. I MADE A DDR3 system and although it wasn't hard to make, it was still challenging to find decent components that all match at decent prices. Plus DDR4 has a lot more expansion off of it so you have more variety.