Lost Tapes is definitely better than Blueprint. "Purple", "Doo Rags", "U Gotta Love It", "My Way", "Nothing Lasts Forever", "Black Zombies", "Fetus", "No Idea's Original" and "Drunk By Myself" are better than "You Don't Know", "Heart of the City", "Never Change", "Girls, Girls, Girls", "Renegade", "Izzo", "Takeover", "Lyrical Exercise" and "Song Cry". Those were my favorite songs from both albums. I'd even say the production on the albums are about even. Aside from "Everybody's Crazy" and "Fetus" just being a bonus, Lost Tapes is nearly flawless.
Blueprint is a classic album that changed Hip Hop, but it's inferior to Lost Tapes, song for song even if by a slight margin.
To me, Lost Tapes plays like an album even though it has songs that were meant for two different albums. The theme is mainly autobiographical and reminsicing on the past. The vibe of Lost Tapes also gives off that reminiscent, memory lane type feel. IMO, Lost Tapes is Nas's most thematically sound album even though it has songs on it from two different albums. I guarantee that if Nas slapped a proper title on Lost Tapes and people didn't know that some of the songs were meant for other albums, people wouldn't think of it as a compilation.