Ride the Lightning is a lot better in my opinion but both are still great albums. RTL has the best of early thrash/speed metal but it also has some progressive influences that would show more on their next 2 releases. Ride the Lightning has the perfect mix and it's a classic. The band matured also from their previous both musically and lyrically, it's a but darker than their first album. It's also their first album to feature Cliff Burton on bass in every track, replaced Ron McGovney which he was the original bassist. Dave Mustaine was fired in 1983 and formed Megadeth, former Exodus guitarist Kirk Hammet replaced him and RTL is their first to feature him on guitar. The band gets their line up together here. All of the songs are great but Creeping Death is my personal favorite.