Judging from the amount of exposure on your broken stem, the Nitto "Technomic Deluxe" [shown above] would allow over 3 inches of insertion, which would give lots more bracing than your busted stems, and you would still have over 4-1/2" of exposure above the headset. The Deluxe at 190 mm. in height may not look it, but is much taller than a typical road stem.

It is not even the tallest stem made by Nitto. Their "Basic" Technomic at 225 mm. is another 1-1/2 inch taller. Even with those taller stems, often exposed to some REALLY extreme heights (and used off-road), I have never heard of one ever breaking... and the "Deluxe" model uses an even better "cold-forging" process - making it even stronger.

Would definitely be my choice!