Big Companies with lots of apps? Or startups with one app? Why do we prefer the latter?

Now, this technically applies to Microsoft and Google as well as Apple, but since Apple is the 'home base' of many starting app developers out there, I decided to post it in the Apple Core.

Basically, I see a trend of people tending to use apps made by startups instead of apps of the exact same purpose from big companies. This isn't always true of course, but in the majority of times, it is. Take Google Currents, for example. Nobody uses it, but everybody uses Flipboard - going as far as to create a brand new account to manage instead of using their pre-existing Google account. And then there's Apple's reminders app. I think we all know that many people prefer third-party apps like Clear, Astrid, or Tasks.

But why? I know Apple's reminders app is an eye-sore, but it's well integrated with Siri, and has geo-fencing. So why do people use other alternatives? I know Currents has much less features than Flipboard, but before Flipboard 2.0, why weren't many people using Currents? And many more.

Is it because the apps are worse in quality (relatively)? Or are we just going with the general consensus. "Flipboard is famous and everyone's using it, so I will too"

This brings another question to mind. If companies like Apple and Google spread themselves out to create apps of different purposes, with the money they have, how is it that they don't always create better experiences for the user than startups with much limited money do? For instance, I know Google makes amazing apps, but why can't they keep Currents feature-rich as Flipboard is? Why can't Apple keep the Calendar app as innovative as Fantastical is? Surely, they have the brainpower to create their own natural language processing calendar.

Any thoughts from the community?

Personally, I've tried my best to use everything one company has to offer. I tried it with MSFT, Apple, and Google. But for me, startups like dropbox sway me away from Drive/Skydrive/iCloud because they just give me this security that they're always working on it; flipboard sways me away from currents because it's just so much more developed and mature; etc.etc.

Would love to hear your opinions!