Round Robin or Swiss or Double Round Robin ?? more just

Which tournament format is most accurate to use for determing which player out of a group of players is the strongest and most deserving of the win.

Well, You're limited by time, normally.

For how many players, and how soon do you need a result?

4 players within a week

A double round robin would be most likely to be won by the strongest player . A single round robin would be better than a swiss with only 4 players . The swiss system is for larger numbers of players . 

What NM Reb said.

If each player can manage 6 games, souble round robin sounds right.

ok if instead of 4 there was 40 and time/energy isnt a factor is a swiss better ?

I like the idea that Greg Shahade came up with for the U.S. championship a few years ago. A Swiss (first 7 rounds for that tournament) then the top 4 players at that point finishing in a round robin against each other with their scores from both Swiss and rr totaled. Combining the 2 formats was an ideal way to use the plusses from both formats. I'd like to see more of the really important tournaments done like that. It was a very good idea.

I've been in a unrated tournament like that its very fun and challenging.

It also addresses the down side to both formats: in a Swiss only it can be claimed that players have different levels of competition than others with same score. In a rr there can be an issue of two players or more pushing for the top spots nearing the end of the event and one or more having an opponent(s) nearing the end that have nothing to lose by playng poorly, their opposition can't finish well anyway so theyre not going to try very hard. Combining both addresses both problems.

About 10 years ago our club organized a blitz tourney.

It started with a 7 found swiss (with it's own prize money) and results determined wheth er players would end up in the A,B,C or D sections for RR.

It was really funny, all the sandbagging, most top players all had the same very original thought that winning the B would be easier than to place in the A, so they all threw games in the swiss to ensure entry to the B, where they ended up playing each other anyway for half the prize money :)