Rainlendar vs Kontact - KOrganizer : Which is Better?

Rainlendar

Rainlendar is a calendar program for Windows, Mac OS X and Linux. Developed by Rainlendar

License: Freemium

Apps available for Mac OS X Windows Linux

KOrganizer is the calendar and scheduling component of Kontact, the integrated personal information manager from KDE. Developed by KDE

License: Open Source

Apps available for Linux KDE

Feature	Rainlendar	Kontact - KOrganizer
Customizable
Sync with Fantastical
Sync with Google Calendar
Multiple languages
Apps that Sync with Google Calendar
Syncs with various services
Scheduling
Todos
Material design
Data export/import
IFTTT integration
Reminder for deadlines
Calendar integration
CalDAV
Exchange
Built-in RSS reader
CardDAV
Task Management
Emacs integration
Web-Based
Command line interface
Sync with iCloud
Week Planner
Built-in Calendar
Events
Notifications
Email tracking
Run in background
Bundled with Windows
Artificial intelligence
Google Calendar integration
Contacts
Convert Email to Task
Feed Reader