In the Classical period, C major was the key most often chosen for symphonies with trumpets and timpani.
Early classical symphonies in the key typically ended in C minor but with a picardy third for the very final chord.
Following Beethoven's precedent, most C minor symphonies of the Romantic period end in C major.
Another option is to end in E-flat major (the relative key), as Mahler does in his Second Symphony.
Symphonies in D-flat major are very rare and one has to look beyond the standard core repertoire to find them.
So is Olivier Messiaen's Turangalîla-Symphonie, as several of its movements including the finale are in that key, although it could be excluded on the grounds that it is very far from traditionally tonal.
Though it has just three sharps and its relative major was used somewhat frequently, F-sharp minor was an unusual choice of key in the Classical era.
98 is credited as the first symphony written in B-flat major in which trumpet and timpani parts are included.
However, Joseph still gets credit for writing the timpani part at actual pitch with an F major key signature (instead of transposing with a C major key signature), a procedure that made sense since he limited that instrument to the tonic and dominant pitches.