I was wondering about the various Cisco simulators that are available such as Pearson, Boson, Router Sim and Lammle Sim that came free with a ebook I purchased but seems limited which I found online so far.
Is there a particular one that is recommended or any that should be avoided?
Do you recommend purchasing any Cisco hardware for the courses?
There are a couple of options when preparing for an exam: You can use simulators and/or emulators. Or you can use real equipment.
Ideally, every person would have the equipment they need and not have to worry with limitations of the number of devices. The reality is that with equipment, it also requires you to know more about design than you might know. Hands on is cool but it has it's limitations to build the "Ultimate Lab", you would spend too much money.
Simulators, you have design control and are not limited by number of devices. Your limitations are along the lines of what you can actually do. The reason is that simulators tend to only include the commands and the output related to that LEVEL of training. Providing for limited commands and "canned" output. This means the commands are not running on the IOS but just generating a predetermined output for you to see.
Emulators, are limited to routers. Cisco switch emulation is not currently possible due to the ASICs. Emulators will virtualize the router hardware but you must provide the supported Cisco IOS to run. www.gns3.net But they are resource intensive and require you to know how to get the tool to run before using it.
So...I wouldn't avoid a particular simulator but I would be aware of the limitation of your options. And understand what you're getting!