DD-WRT isn't open-source though. OpenWRT is.
Out of the two of them DD-WRT is more "hacky" and duct-taped together, while OpenWrt is more "pure". This can mean that DD-WRT feels more feature complete at times.
I bought a pair of them at the time. Kept one (N600) until I needed a 'mesh' and sold it on eBay about four years ago. Replaced it with an Orbi system that doesn't need to phone home (not sure such things are still available in the consumer market).
I ended up adding support for the G300NH2 model for OpenWrt.
The only time I’ve installed OpenWRT was on my WRT54G, which was in service until it was replaced by one of the Buffalo WZR’s.