All of these are around grade 7 (some a bit lower, some a bit higher – but you should be able to cope):
Beethoven:
Op. 49 no. 2
Op. 49 no. 1
Op. 79
Op. 14 no. 1, no. 2, no. 3
Op. 10 no. 1, no. 2, no. 3
Op. 2 no.1
See also this thread for a discussion on the relative difficulties of Beethoven sonatas:
https://www.pianoforum.net/cgi-bin/yabb/YaBB.cgi?board=repo;action=display;num=1081594962Haydn:
Haydn wrote around 60 sonatas, all of great musical quality, all underplayed. Almost all of them are around grade 7. Here are some of my favourites amongst the easier ones:
Hob. XVI/8 in G, XVI/9 in F, XVI/10 in C, XVI/4 in D, XVI/12 in A and XVI/27 in G
Mozart:
K 545, K 282, K 283, K331 (the one with the “Turkish March”) and K 570 are the easiest.
Clementi:
You may want to investigate Clementi’s sonatas (not the sonatinas), which Beethoven thought were superior to Mozart’s (and I tend to agree).
C.P.E.Bach:
C. P. E. Bach pretty much invented the classical sonata (and sonata form) and was a huge influence on Mozart. Almost forgotten these days and almost never played, his sonatas are real gems. Again, all of the sonatas are around grade 7-8, so you should be able to manage. I particularly like w62 in G.
Two obscure composers, Christian Latrobe (3 sonatas op. 3) and Fanciszek Lessel (3 sonatas op. 2) are also around grade 5/6 and the style is similar to Haydn.
Best wishes,
Bernhard.