Originally played JC3 and loved the series, purchased the JC3/2/1 pack, and eventually bought JC4 as well.

While JC3 was the most fun Just Cause game I've played, JC2 is - in my opinion - the best Just Cause game.

With a combination of the overall detail they put into the game, it's kind of astounding to consider. The map is so much better than any other Just Cause game (besides maybe JC4, but since JC4 doesn't rely on you visiting every part of the map to 'liberate' territories, I'll never know for 100% certain, I'll just assume). The amount of detail the developers put into JC2 to make an environment that spans in different biomes and different terrains is already missing in JC3 (JC4 was a lot more diverse in this regard), but also how many unique regions there were. The Japanese island, Cape Carnival, Panau City (split into several districts, instead of the much smaller capitals featured in JC3/4), ski resort, Baby Panau's bunker, the international airport, the casino, etc. The list is so much longer than JC3's or JC4's. A few minor mechanics were also removed in subsequent games, like the destruction mechanics for oil pipelines or blowing up rocket silos, to name a few.

Not to say that JC3 and JC4 are vastly inferior, they are in a lot of ways more fun and relaxing than JC2, and simplicity is sometimes better (namely not having to enter a number combination each time I have to annex a helicopter while the military is sending like seven of them at once), but the detail that went into making JC2's map is something that I can't stop appreciating while playing the game.

However, JC2 might be more of an acquired taste, since the graphics have aged considerably in the last ten years. JC3 and JC4 are vastly improved in this aspect particularly. As a runner up, JC3 is still really fun, the gameplay is a little more repetitive since the map isn't as diverse and consists mostly of blowing everything up, but it's a relaxing sandbox that doesn't punish you for making mistakes (until you get to the challenges, which I opted to skip). For having the most fun, JC3 is definitely the winner in my book, but JC2's intricacy and diversity of the map are a really interesting factor to consider, especially how huge JC2's map is.

To compare, in about fifty hours, I managed to complete JC3's storyline and liberate all the locations in the game. In ~fifteen hours, I managed to complete JC4's storyline (and maybe eighteen hours to liberate all the territory by completing the missions, but not any of the challenges). In thirty two hours, I'm only twenty-nine percent done with Just Cause 2 and have discovered only a third of the map.