Simply the best (better than all the rest :)
If you are serious about trading you need to avoid the bucketshops and use a decent trading platform like LMAX.
LMAX is quite simply excellent.
Unfortunately 90% of people don't have sufficient trading experience to realise why - which is why 90% lose money.
Spreads on LMAX are fantastic, execution is instant and you even have some visibility on depth of market etc.
This is a different league from traditional fx brokers.