Ignore the last two paragraphs. I downloaded Calendar 5 to see what their widget does, and it doesn't do task, only events. Bummer.
I used to use Calendar 5, until I tried Fantastical. Both are excellent, but I like the look and view options in Fantastical 2 just a bit better. And now the widget appears to be better too.
Here are the two widgets. As you can see Fantastical shows both events and tasks (but only four sadly). You can also tap on the tays in the widget to show the events/tasks for that day.
Tapping on either widget will take you to the app. So even if you stick with Calendar 5, adding that widget would offer you a shortcut to it instead of the Reminders app.
And what the main app looks like. You can adjust or eliminate the different areas if you need need more room for the others. Also, like Calendar 5, natural language input is supported, and syncing withe the native calendar/reminders or Google.
Have you tried using the Today view's widget for Calendar 5, instead of the Reminders widget? Even if it does not show you the up-to-ten items you'd like, at least it would launch Calendar 5 instead of the Reminder's app when you tap on it.
I'm not sure how the Calendar 5 widget works/looks. With Fantastical you can have both a calendar and item view (limited to four items), but you can tap on the dates in the calendar to see the items for those days.