Which is better? IRDS of RGK(Racing Game Kit)

Hi! I can't decide about these engines. Which is better?

 

RGK is essentially abandoned, it hasn't been updated in many months, nor has the author responded to inquires. Includes source code version with access to source code repository, but since the author does not reply to inquires, you might not receive access.

IRDS does not include source code. If you discover a problem or performance issue in the profiler, you'll have to wait for the author (who may be involved in his own projects). Packages with no source are risky and generally not recommended.

Alternatives:

GI Racing (From Game Institute) - $49 (1 year access). Includes source code and access to other game development tutorials. Likely doesn't yet work with Unity 5.

Smart Car AI - $10, includes, source code but you will have to get "under the hood" to add features, or a complete racing manager system. Doesn't yet work with Unity 5

UnitySteer - Free, includes source code, but also needs to be customized for vehicle usage.

Flat Tutorials - Free Racing AI tutorial series on Youtube. Would need customizations, but also re-coding for Unity 5 wheel collider adjustments.

Good luck!

Edit: 8 Oct 2015

Racing Game Starter Kit - $30. Includes source code. Complete racing manager system. Author is very responsive and helpful, and is continually adding features.

Realistic Car Controller - $30. Includes source code. Includes a very generic AI solution (using Navmeshes) that would likely need more work "under the hood" for a complete racing manager.