When comparing Solar 2D (formerly Corona SDK) vs Panda3D, the Slant community recommends Solar 2D (formerly Corona SDK) for most people. In the question“What are the best 100% free and easy game engines for beginners?” Solar 2D (formerly Corona SDK) is ranked 5th while Panda3D is ranked 6th.
Specs
Ranked in these QuestionsQuestion Ranking
Pros
Pro Very simple to use

Pro Free
Corona SDK is completely free. That includes pro-tier plugins.
Pro Corona Simulator
Corona SDK ships with Corona Simulator, which runs your game/app directly on your PC/Mac and updates every time you make changes.
It provides immediate feedback to your actions, you can see your changes right on the screen, without necessity to make build to device. Getting instant feedback really boosts tenfold prototyping and development speed.

Pro Good documentation and lots of tutorials
Pro Content scaling
It's easy to create a game that looks good on many different sized mobile devices.
Pro Live builds - update builds running on a device automatically
With the live build feature, once you have created a build and installed on a device, you get lightning fast turnaround times because any change on the code or data is updated to the devices running the game (within the local WiFi) immediately. So changes can be tested on the real hardware within a very few seconds.
What's even more impressive, this even works flawless with multiple devices running the game. You have to use it to learn how good of a feature this is while development and even more, while doing QA. Imagine fixing bugs and everyone of your QA team/friends/whoever helps to get your game done, has all changes on his device without doing anything but waiting 5 seconds - outstanding.
Pro Lua syntax
Uses the great and easy-to-learn Lua programming language.
Pro Very comprehensive API
It's very quick to get things up and running with Corona SDK. The API is extensive and while it's not 100% feature-complete with the iOS API, it's close enough that you could create tons of games and never run into a roadblock.
The API docs can be found here.
Pro Amazing learning curve
Corona does not throw photoshop-like madness full of buttons editor. You can go as fast as you want, learning and building game from ground up. Eventually, you'll learn how much corona is doing for you. But to start you don't have to master complex editor software. It's a great tool to learn to start game development if you want to learn how to program and make games. Your experience will be 100% transferable to any other Pro game engine.

Pro Cross-platform desktop and mobile
Corona works on OS X, Windows and Android (including Kindle Fire & Nook).
Pro Marketplace for 3rd party plug-ins

Pro Great community

Pro Ability to call any native (C/C++/Obj-C/Java) library
Pro Completely free
Since Corona SDK became Solar2D, it's completely free, as only some third-party plugins are paid.
Pro Open Source
Since Corona SDK became Solar2D, it's completely open source under MIT license.

Pro Well supported

Pro Free, open-source, and permissive license
The liberal license allows use of the engine for any purpose without restrictions or royalties.

Pro Will be very easy for developers already familiar with Python
Although it's possible to use only C++ to program in Panda3D, all its power is available to the Python scripting language, while not trading in performance since the performance-critical parts are implemented in C++.
It has a powerful binding layer that exposes the vast majority of the API via Python-based interfaces.

Pro Supports most popular physics engines
Panda3D has in-depth integration with industry standard physics engines such as Bullet, NVIDIA PhysX and ODE, but also offers a simpler built-in physics engines that will cover more basic needs.

Pro Flexible scene and object hierarchy system
Creating weird world constructs is generally a breeze. The node system the engine runs with allows to build self-looping worlds and, on large scale, non-Euclidean scenes without having to introduce a huge amount of custom code.

Pro Powerful profiling and debugging tools
Panda3D has a suite of powerful tools to help track down performance bottlenecks, memory leaks and examine internal state.

Pro Supports browser deployment
Panda3D offers web plug-ins that allow deployment of an application to all major browsers. A WebGL port is in the works as well.
Cons
Con Free, but not completely
Con Making a device build requires internet connection
To build your app for the device (iOS/Android/AppleTV) Corona requires to fetch resources from online. This would include base application template and plugins. This allows not to perform local build or use Xcode or Android Studio to do a build. Even Large games/apps would build very fast with good internet connection.
Your code never leaves computed. Corona SDK would transfer some information to determine which plugins and pieces has to be transferred in order to make a final steps in build.
As a bonus - you get basically one button press to get from your Corona Simulator game to game on a device.
Con No unified editing program
Unlike Unity and Unreal, Panda3D doesn't currently offer a single, unified editing program in which objects can simply be dragged in and assigned properties (although third-party solutions are available). Developers are expected to design their scenes in a modelling program like Maya or Blender instead, and import them into Panda3D using Python code.
Con Limited tutorial
Step by step tutorial is limited. Manual is too general and short without examples. Samples are too complex for beginners.

Con Direct3D support is behind
Direct3D support not up to par with OpenGL support, only version 9 is supported.
Con Terrible compilers support
Does not support any other compilers then MSVC on Windows, neither Clang nor MinGW.
Con Developer isn't very competent
Panda3D only has one developer and he utterly fails to fix problems with his engine, instead focuses on style guidelines and breaking code.
Con Loading Pandas3d will change your builtins to contain non explicit references to non-standard helper functions
A lot of the pollution comes from storing global state. Instead, you can store and update the global state of a namespace instead. As for the built-in pollution, you can make a wrapper that backs up builtins, imports pandas and then restores builtins, though this may not work as pandas almost certainly uses it's extra builtins to work. The best thing to do would be to explicitly import the same objects that are in the builtins over the top of the modified builtin namespace, although it doesn't remove the code smell, it helps to make things look less (if not at all) magic.
