Metatrader 4 for trading, because it is the only choice by my current broker. Metatrader 5 for analysis - because it has more timeframes, which is essential for my trading. NinjaTrader for 15-second charts and back-up quotes, because Metatrader 5 doesn't have second-charts built-in and the custom indicator ones take a huge toll on my system.
NinjaTrader is a quite awesome platform for analysis/charting also, although I don't use it as I'm more used to the Metatraders. TradeInterceptor and JForex are quite good also, but are Java software - a.k.a. quite resource-hungry.