Railo is the best CFML engine.
I guess you'll be wanting me to validate that statement? Well I'll make a start on that in a moment, but first I think I'll post a few disclaimers to pre-empt any potential whiney people.
I have nothing against Adobe, NewAtlanta, CFMX, nor BlueDragon. They're both great companies/products - without the company formally known as Allaire, I'd never have had my life enriched by the joy that is ColdFusion - and BlueDragon is no doubt a fine product if you find yourself stuck using that .NET thing. ;)
But Railo is better than both of them, and here is why...