No easy answer to this. The impossible to get Tomenosuke is the best I have seen so far, but they sell on the secondary market in Japan for over $4,000. If and when they ever go on sale.
Rich Coyle is finishing work a new version himself that I am holding out hope for. It is looking pretty promising though to be a top notch replica of the hero gun.
The Offworld is okay, but does have too much plastic in all the wrong places. It is durable enough for costuming, and can be painted up to look pretty nice. Not really accurate either, but not as far off as many of the ones from the late 80's and early 90's.
Sidkit's are also pretty hard to find now, especially with the upgraded parts.
Hartfords are the coolest, because they are functional airsoft or PFC cap guns. Also very durable and well made. They are also not being made anymore and their prices are going back up. Still not 100% accurate and based on on a S&W revolver instead of a Charter Arms. In your hand they feel like a real gun too.
Rick Ross's kits are not 100% accurate, but are sculpted pieces of art, and may be cooler looking than the real thing. They can also be had very affordably when you can find one.
In the end it all depends on what qualities/uses you are looking for in a replica and what you are willing to pay. Basically what Mark just said
Andy