What do you think is his least strongest??
I have no idea what gives you this impression.
If you don't want to discuss Vaughan Williams that is up to you.
Elgar's piano writing in those penny-dreadful piano and orchestra works, the Concert Allegro and the reconstructed piano concerto certainly leaves quite a bit to be desired, yet the writing in the violin sonata and piano quintet is surely rather more idiomatic.
The first movement of Grieg's PC in a is the highlight of the whole concerto in my opinion. I especially like the Intro.
I think my top 2 favourites are:1) Rachmaninov no. 32) Tchaikovsky no. 1
I was wondering what's the most wonderful piano concerto?? Mine is Tchaikovsky's no.1 in Bb minor.
I really like Liszt's second, though I wouldn't call it my favorite.
Bach's 5th Brandenburg. De facto, it's a concerto for keyboard. As well as the best music ever written. De gustibus non disputandum est.