MB Trading : mbtrading.com
FXAll for those who have deep enough pockets or can set up as institutional traders.
CitiFXPro
FinFX
Interactive Brokers
Pepperstone
Dukascopy
the best in my opinion, is FXAll but if you don't have the cash yet, then MB Trading is next best for retail traders, with IB and Dukascopy. MBTrading, before offering FX, they were and still are offering stocks, options, futures for the past 20 years. so they have been around.
Dukascopy is a mixed bag. i never had any issues with them, but i keep hearing people complaining about shallow liquidity pools.
FXAll is really for professionals.
the rest, is OK, not the best. IB probably better than the remainder.
all this being said, i would not use a broker that only offers access through MT4. why? because MT4 is sh|t when it comes to managing your trades. you want a professional platforms for that, so you can enjoy the flexibility and see the order book as well, none of which is available with MT4. and even though those non-MT4 platforms might seem a little harder to use at first, so what? if you can't learn and adapt and overcome, meaning if you can't even do what is good for you, then you have no place in this business. i say this because i see way too often so many rants on forums from people complaining that this or that is not as easy as MT4, as if that makes MT4 a good platform. it doesn't. so i hope, for your sake, you bite the bullet and start using the real tools.
anyways, don't take my word for it. just test drive all of them.
ok, end of rant. ;-)
P.S. 0: forgot to mention WH Selfinvest: sorry--typo--it's an STP broker when trading FX, but has deal desk for CFDs--they have a very good reputation in Europe, and their FutureStation Nano is awesome and your funds benefit from being in luxembourg (read up on that, no time to explain details), BUT they only open accounts for European citizens.
P.S. 1: STP: the quotes are obtained directly from a bank.
P.S. 2: ECN FX brokers allow clients' orders to interact with other clients' orders. ECN FX brokers provide a marketplace where all its participants (banks, market makers and individual traders) trade against each other.
P.S. 3: damn i am scattered tonight... STP means no level 2 DOM as only with an ECN do you trade against other customers of the same broker, and each client basically acts as a mini-market maker. the aggregation via STP doesn't allow clients to see the order book depth, if my understanding is correct.
P.S. 4: so, if an ECN broker is dishonest, they still could take the other side of the trade, and play with the feed they give you.
P.S. 5: so STP or ECN it's all moot... testing the broker live is the only way really to tell.
P.S. 6: STP FX brokers send orders directly from clients to the liquidity providers such as banks which trade on the interbank. The more there are banks and liquidity in the system, the better the fills for the clients.
ok am done. i need sleep ;-)