Currently EU players face hellish lag connecting to the JP servers. At the end of the day though, it boils down to lag and playability.
My hope is that the lag from EU> NA, NA > JP, and any permutation you can think of is less than it is today. The only exception would be JP > NA or EU servers, since they've had a natural benefit of low pings (although if the 25th talk show is any indication, they get the lag problems on things like ifrit too). If that's the case, then this is just a matter of coordinating your ls (and future grand companies) on which server to select come ARR.
