Jaime Hernandez: The1950-S Roosevelt Dime is considered a better date. It is about the fifth lowest mintage in the silver circulation strike series, with a mintage of about 20 million coins. Its mintage is actually a bit higher than the 1949-S, 1955-P,D, and S Dimes. However, only the 1949-S commands a higher premium than the 1950-S in the lowest grade to MS63 grades.
Even though the 1955-P,D and S have lower mintages, the 1950-S brings a higher premium as it is considered a more difficult coin to find.
MS64 - MS66: Coins in MS64 - MS66 are not considered scarce but they are tough to locate.
MS67: In MS67 condition several hundred examples exist but they are considered scarce.
MS68: There is about a handful of coins that grade MS68 but those are unquestionably the nicest examples available with none being finer. (See PCGSCoinFacts PLATE COIN)