Hard to pick between Chile and the Netherlands but I'm going with the Netherlands (I'm half Dutch).
The Netherlands have never failed to progress from the group stage since 1974 when they first entered a professional side (Holland's only two previous appearances in the Finals were in 1934 and 1938, fielding only amateurs, when entry was by invitation and teams only played one first round game, the winner making the quarter-finals). Of course, they never made the Finals in 1982, 1986 and 2002.
Amazing to think the Netherlands only have forty years of post-war World Cup Finals history - much less than most other major countries.
Dutch clubs were weak before the 1960's and the national team only allowed professionals from 1956 when Holland's first pro league was formed.
By contrast, Chile have only made it past the group stage three times in eight World Cup Finals appearances...
The Netherlands have appeared in the Finals only seven times since World War Two but have made the Final three times.
Chile's best performances have been a third-place when they hosted the Finals in 1962 and two Round of Sixteens.
Stats don't always predict current performance - but I'm hoping so !!!