Population
Phinny > > > Ragefire > Lockjaw
Definitely the highest population of any server is Phinny. Ragefire has the population of some of the more populated LIve servers, with LJ generally much less (you can log in and check bazzar for Traders as a general idea of population).
Expansion Unlocks
A new expansion opens every 90 days or so on Phinny, and I believe it gets shorter after Gates of Discord.
New expansions open every 6 months on Ragefire and Lockjaw, dropping to 3 months after GoD.
Experience Rate
Phinny has a very slow experience rate compared to live servers. Ragefire and Lockjaw exp is much faster (though still slower than live servers)
Some things to understand.
Ragefire and LockJaw have the exact same rule sets. Ragefire has a greater population than Lockjaw. There is no real reason to choose Lockjaw over Ragefire. Toons from Lockjaw can transfer to Ragefire however, so You could start there and transfer to Ragefire at some point if you preferred (for some reason)
Ragefire (and LJ) have been at the level 60 cap for over a year expansion wise. I would imagine you are going to have a hard time finding groups at level 1-40, though I'm sure it's possible. Everyone is already level 60 with level 60 alts at this point. PoP opens in about 2 months. Plenty of time to hit level 60 and get some AA's even if you play casually.
Some questions to ask yourself.
Do you like to Box? It's easy on Ragefire, it requires multiple computers to do on Phinny.
Do you like Macroquest? It works on Ragefire, it does not on Phinny.
Is the 1-40 group game super important to you? Phinny has a far more robust population across the levels as well as less boxers. You will likely have a better time finding groups and leveling your way up to 60, and be able to spend more time enjoying it due to slower exp rates. Ragefire 1-40 game can be rough as a solo player, but the exp rate is faster, and it's much easier to box a few toons for yourself (MQ helps!). On Ragefire once you are level 40 finding groups shouldn't be too hard.
How do you feel about Raiding? There are a plethora of guilds to choose to raid with on Phinny. You will be able to find one that fits your playstyle/schedule. On Ragefire there are 3 "Top End" guilds rotating Vex Thal, and 2 or 3 other guilds killing smaller Luclin targets, and doing NTOV etc. Most every guild is US primetime with the exception of 1 which is EU primetime. Ragefire will have less choices for you if you want to raid the Top End stuff in era. Shouldn't be hard to find a guild on either server, and you should have plenty to raid as well.
Do you like fast expansion unlocks? Or Slow? Expansions unlock at twice the rate of Ragefire (3months vs 6months).
So use that to choose what fits you best.
As a Ragefire player I can attest to there being a great community. Pretty much all the guilds get along, everyone is friendly
