Their featuresets don't exactly match, but both firmwares have so many features I'll never use that it's ridiculous. Really it comes down to personal preference. I like that ddwrt doesn't feel constrained by the linksys interface and featureset.
I do think DDWRT is better supported and less likely to be dropped than hyperwrt+thibor, although hyperwrt as a whole is a larger project. Give it a shot, it really does rock your socks.