From my perspective, FP Markets is a reliable broker; they are my go-to broker for Day trading as the trading conditions offered in their Raw Spreads (ECN) account is ideal for scalping. The spreads are some of the tightest starting from 0.0 pips for majors like EURUSD, GBPUSD etc. Execution is pretty quick and most importantly, no spread widening issues even during a volatile time.
As for me, the best broker is the one that has a lot of clients and has become a trade and reputation among other competitors.
I do know a couple of good forex brokers but to call one as the best is more of a personal thing I believe as each trader has different preferences. For me, Fxview is one that I can call the best and the reason can be attributed to their tight spreads, affordable commissions($2) and fast withdrawals.
It is actually not necessary that old brokers are more efficient with their services. It is in fact the opposite most times.