my all time favorite is an X pattern of Vintage30s and G12t75s
this is the same set up that is stock on the matching 4x12 for the almighty Bogner Uberschall
Definitely best suited for classic rock and everything or anything more agressive
If was playing traditional blues, jazz, or country, Id look elsewhere.
Otherwise its an amazing well ballanced set up, which works great with many many different high gain amps.
vintage 30s are famous for their midrange push, which for modern guitar stylings is important because this is what you need to get your guitar through the mix (though using the midrange knob well works wonders too)
however, vintage 30s are known for flubbing out a bit on the lows, and not having the greatest defined highs.
This is where the g12t75 comes in. By comparison its low end is very tight, focused and the highs are much more defined and shimmering.
The result is a very very balanced yet dynamic sound regardless of where you are playing on the fretboard, or playing crunchy rhythms or singing leads.
Whats funny for me, is I actually discovered this combination before ever hearing about it being done. I was once just messing arround in my studio a few years ago and ran both my 1960 (g12t75s) and Trad Recto (v30s) at the same time with my single rec. I was amazed at howmuch more ballanced and defined the sound seemed than using either caby by itself. I started having my suspiciouns that maybe I just liked it more because of all the extra being pumped arround by the fullstack, but I started doing some homework and found that many people were using this combination.
I really cant speak enough good things about this combo!