Start with the first one, Phoenix Wright: Ace Attorney, otherwise you'll miss out on references and such.
Technically Ace Attorney Investigations: Miles Edgeworth is the best game in the series, but only because it's harder to get confused.
Personally I find AAI: Miles Edgeworth to be the best in the series in terms of game play. I find the whole moving around and the logic system to be refreshing... I find AJ to be the black sheep in the family. I found it not as engaging and some of the cases were so drawn out... plus it seems to introduce some "contradictions" of its own to the established series storyline involving phoenix and crew.
Am I the only one who liked Apollo Justice...? I admit it's probably the weakest in the series, but it's still a great game, and I LOVED the last cases.. they were just really entertaining. I loved the characters too :S
Aaanyway, yeah.. play them all starting with Ace Attorney 1, because that's the order they were meant to be played and you'll probably get the best experience
Also, how is Investigations the best in the series?? It's a nice change from the repeated courtroom games, and the logic is straightforward, but its far from being the BEST game in terms of storyline! :/
Phoenix Wright Ace Attorney
Phoenix Wright Ace Attorney: Justice for All
Phoenix Wright Ace Attorney: Trials and Tribulations
Ace Attorney Investigations: Miles Edgeworth
Apollo Justice Ace Attorney
Personally I played the demo of Apollo Justice they offered through the Nintendo Channel first and loved it then finally came back to the games with the release of Phoenix Wright on WiiWare which I'm about half way through and I have enjoyed almost all of it (having to go back and forth between locations for evidence got a bit tedious). Then I got Miles Edgeworth which adds a new twist of gameplay which looks good although I'm not past the first case yet. Since I've effectively had a taster of all 3 character's games I'd say that PW is a good starting point with it's sequels probably following suit although they may get repetitive. Then if you're looking to refresh yourself, Miles Edgeworth it is.
i always hated the investigation part and loved the courtroom part of a case.it's good to see that courtroom stuff has been implemented in the investigation part in AAI:ME but i miss the courtroom very much now.the humour of the bald old judge,the atmosphere of the courtroom.those are the things that made the series so entertaining to me.so i don't like the new game very much.but it's still a good game.at least better than AJ.
It's always best to start with the first game of a series which has a good continuous storyline.
I like the last case of the 3rd game most.