I still rate
Remember The Milk above the rest. I've bought and spent time trying out Things, OmniFocus, Toodledo / Pocket Informant, IMExchange with Outlook syncing, The Hit List, Simple Task, and have Never found anything to make me want to stop using RTM. Btw, the only reason I tried them in the first place, rather than just sticking with RTM and ignoring the rest is because I'm seemingly addicted to trying task mgmt apps. Not sure quite why
RTM syncing has always been seamless and reliable. It's hugely customisable, you can get what you want out of it. Yes, it doesn't sync bidirectionaly with Outlook or iCal, but running it as a standalone app in
Fluid on my MacBook works really well for me.
I've found it's perfect for my needs. I use it for personal/family tasks/todos, project and task management for work, and more recently I've found it's a great way to set out training plans and logs for my running & cycling.
The longer I've used it, the more I've discovered I can do with it, and the more productive I've become.
I know some are turned off by the $25/yr pro subscription, but it's been well worth the price for me.
Recommend it to anyone who's not yet tried it.