There are pros and cons to the various options:
1) Vintage sights:
I have vintage Marbles or Lyman tang sights on two of my three pre-64 Model 94 carbines as well as on my 1926 Model 94 rifle.
They come in various configurations but my favorite is a Marbles with both a lock and a flip adjustable large and small aperture.
They also come in the slightly less snazzy model with screw in apertures and you can either get them in a few different aperture sizes:
Alternatively, get a Merit Adjustable aperture for them in either the 1/2” outside diameter Hunter or 3/4” diameter target models.
The pros of the vintage sight approach is that they are very well made and are very practical in use. They also look right on a vintage rifle or carbine where the new ones just don’t.
The cons are they are expensive and hard to find in excellent condition, and they lack windage adjustment. The tang needs to be properly drilled so that the sight is perpendicular to the tang and windage is adjusted via then front sight for zeroing purposes.
2) The new Lyman Number 2 sight:
These were the first of the modern reproductions to show up and they did so in the mid 1990s. The major advantage is they are readily available and are not al that expensive, and still allow you to get near maximum benefit offered by a tang sight (maximized sight radius, not having to focus on a barrel mounted rear sight, and being able to adjust the aperture size to get maximum depth of field in various light conditions).
They are not quite at the same level as the old Lyman sights quality wise and they use an o-ring for friction on the elevation barrel, and it also doesn’t have windage adjustment, but it’s still a very good sight. My pre-64 Model 94 carbine in .30-30 with a my Model 94 LF in .38-55 will all shoot between 1.5 MOA and 2 MOA with the Lyman No. 2 at 100 yards. The new Lyman No. 2 sight:
3) The new Marbles tang sight:
This reproduction came a bit later, and it comes in a standard version as well as a version with interchangeable risers. (I’ve never found a need for the higher risers with .30-30 and .38-55 classes of cartridges and the standard model has worked fine).
It’s a bit more expensive than the Lyman, but a lot less expensive than a vintage sight. It also offers a click adjustable windage knob. That’s a mixed blessing as that knob is a bit large and rubs a bit on the hand during recoil. Still, I have one on my BB 94 in .375 Win as well as on a Model 92 in .45 Colt and it’s not objectionable.
The riser also doesn’t stand up quite vertically on the tang on the Model 94, but it’s not enough to notice looking through the sight.
It’s my most common tang sight as over all it offers the greatest degree and ease of sight adjustment. I have them on two Rossi 92 rifles in .357 Mag, a Rossi 92 carbine in .45 Colt, a Model 1992 in .45 Colt, as well as my BB94, and a couple of 9422s.
It’s a good sight. It’s important to understand however that even though it has windage adjustment the tang still must be drilled so the sight is vertical over the bore centerline, so that windage doesn’t change as the elevation is adjusted. If it’s not plumb with the bore, you’ll need to shim it so that it is.
You can see the difference in the picture below with the Marbles on the top and the Lyman on the bottom.