I have read, and it sounds not unreasonable to me, that Weller 12 YO (which is not easy to find in my neck of the woods) is the 12 YO wheat bourbon that Buffalo Trace makes for the Van Winkle's 12 YO Lot B that was NOT selected for use in their bourbon. My own comparison of Weller to Van Winkle Lot B (which is darker in color) reveals that Lot B is superior in complexity and subtlety to the Weller....... a noticeable, but not great, difference.
Now, how does the Weller 12 YO wheat bourbon compare to the newly released Beam 12 YO rye recipe bourbon?
Herein lies an excellent example of the difference twixt a corn/wheat recipe bourbon vs a corn/rye recipe bourbon. The Weller has the softer sweetness one expects from a wheat bourbon. The Beam has more of the rye 'scratch' in the mouth that rye bourbon lovers look for in their favorite bourbon (e.g. our BE friend Squire and his love of the wonderful Old Grand Dad, a Beam bourbon). Rye awakens the palate, while wheat gives it, by comparison, a bit of repose.
The Beam 12 YO does not 'look' like a 12 YO bourbon, its color is significantly lighter than the Weller, implying less barrel influence. And, the Weller taste confirms that impression, it does offer more barrel sweetness. The Beam tastes like a younger bourbon than Weller in that respect.
The 12 YO Beam is much like the Beam 8 YO (of my memory) a respectable whiskey, but no more than that. It strength is that it is superior to the White Beam (greater subtlety), its weakness is that at its price range it is inferior to Knob Creek (for which I have an affection that can only be accounted for by my affection for that wonderful, but too often absent, character of bygone BE days, Saint Bunghole).
The Weller 12 is probably not better than the Beam 12 YO, just different. For the money, the better bourbon in this price range $30 to $40 by far is the Four Roses Single Barrel.......... in my opinion, a more complete whiskey.