In my opinion nothing fits like factory. Even the after market handguards will require a free float conversion nut and after that they dont exactly mesh with the upper. Only the factory hand guard will match the upper and angle out to the fore end. Not to say that aftermarket will look bad.
The factory M-LOK is as light as I can find and the quad rail isnt much heavier but it is heavier. Depending on what you want. The M-LOK is more desirable as most folks have the quad rail. Like I said if you need a factory quad rail let me know.
Here is the link to the VISM Rail Bassyaks mentioned.
NcSTAR Vism M and P 15-22 Keymod Free Float Handguard VMP22FFKMR Up To 19% OFF New Product
Notice how it doesn't flare down at the end where it meets the upper this means instead of a good even flow the gun will have a ridge where the two meet. Since bassyaks has this rail maybe he can supply a picture so you can see what I am talking about. Its all about what your looking for.
For me I was unwilling to add weight and I wanted clean lines like factory. M-LOK was the only candidate left.