Having an iPad that can be easily removed, and which can be loaded with whatever apps you need, is a big plus. The Garmin is less flexible in comparison, but has the benefit of being dedicated to its single job.
I advocate SkyDemon, but I work for them so some might say I am biased! You can do a 30 day trial for free though, so have a go if you have not done so already. You may have flying friends who have an iPad that you could borrow if you don't have one yet...