Between mobile and a desktop wallet which one do you prefer the most and why? Again I think desktop wallets have more open source wallets than mobile, which desktop wallet is the best open-source wallet that you know of?
It depends on the context and size of holdings and purpose of the wallet.
If spending is the purpose, the contents should remain and should go to a mobile wallet. (because you can't take your desktop to the store)
If holding is the purpose, the contents can be larger and should go to a more secure wallet IE: desktop or hardware. (this is also good for staking purposes.)
A desktop or a mobile wallet are just tools that we have at our disposal and it is up to us to use them for the appropriate purpose, when it comes to long term holding, a paper, hardware or desktop wallet are the best options as you can keep them offline and if you can secure your physical location as well then the chances you will get hacked drop considerably.
However if you want to spend some of your coins at a local business then that is where mobile wallets shine as you can use them to buy whatever you want while you are away from your home, however I would never use a mobile wallet to store my coins long term as smartphones are online all the time, which gives hackers many chances to steal your coins.