Recently moved jobs from a location that was heavily into Gomez for synthetic browser transaction generation / response time monitoring, now at a location that uses Neustar, but their contract renewal is coming up.

I'm seeking opinions on either of these tools (or any other synthetic monitoring solutions) that individuals have found to be cost-effective and able to support Safari browser emulation, which makes up ~60% of our web traffic.

What tools have folks out there used for website availability and performance monitoring?