I am just ramping up on trading, so my comments are not seasoned from trading experience. But as a very experienced software developer perhaps my comments can provide some value.
First, I will say that if you are on an Intel-based Mac you don't have to be limited to Mac software. I run Windows using both Bootcamp and Parallels. I prefer Parallels as it allows me to run within OSX. I am not actively using any Windows based apps for trading, but acknowledge that the selection is much larger on Windows, and keep that door open. As I move from paper to real trading later in the year, I will assess whether I want to switch to a Windows app.
I am opening up to using multiple tools as a single one isn't covering all the bases. I like Sherlock (comes with OSX) for quick quotes, although not so much for intraday as they are not realtime.
TradeStrategist - So far this is my favorite of the commercial apps. But I haven't included options and I'm not sure they will support them. Good paper and backtrading.
MarketAnalyst - I need to reevaluate this one.
BlueChip - Not bad for $12, but not extensive enough to use as anything but a side tool.
VulcanOracle - Focused upon finding stocks, not managing the portfolio.
EclipseTrader - Free and Open Source. This shows a lot of promise. With the right broker/data provider this environment could be killer.
Thinkorswim - yet to be evaluated.
OptionsXpress - yet to be evaluated.
From a software perspective, I work entirely in Java and Flex2. In fact, my current project is a trading company which got me into learning the domain and establishing trading skills. Innovations in software take time to reach the public, but the trend is towards service-oriented architecture (SOA). This means that 2-5 years down the road these large proprietary Windows-based apps will start to open up and change into cross-platform apps. The EclipseTrader app is an example. It's plugin architecture means that anyone can add functionality by building a plugin to extend the existing and free trading environment and hit the entire market regardless of OS. Combine those plugins with web services that provide value to any client that taps into it and that is the direction trading apps will go. EclipseTrader is pretty solid for as new as it is (it has never crashed on me), and I'm looking for a broker that integrates well with it. At least those are my thoughts. I'm considering building a paper/back-trading plugin for it myself.