I used to prefer Gmail earlier. But at the moment, due to Samsung+Microsoft services integration, I use Outlook the most, along with OneDrive and all of the other services by Microsoft.

The best thing I like about OneDrive is, I don't need my laptop with me whenever I am going somewhere. I have Office apps in my smartphone which are a literal clone of their PC counterparts.

With OneDrive I am able to access the files stored in my documents folder and other essential folders, and with some tweaks in settings, and folder management, I am able to access the Downloads folder also. Thus no need to have a laptop with me, if it is just for office work only. I cannot do that with Google Drive.
Sure, Drive is also providing a PC app for this feature, but OneDrive comes preinstalled and well, I don't need to look anywhere else, in some special software. The OneDrive folder is there in This PC interface. That is helpful by a lot.
I even have my OneDrive premium payment linked to my Gmail account through Play Store lol!
Kind of a mess. Literally!😅
Superb Opinion