Of all these concerti mentioned, I’d say that Rachmaninov’s 3rd (why “Rach”? why can’t English speakers tolerate more than two-syllable words?) and Brahm’s 1st have the most impressive endings of all. Grieg’s ending is very impressive and beautiful too, but those final orchestral chords are so distasteful that almost ruin the whole effect, imo of course.
Other concerti with impressive endings are Medtner’s 1st (like huge surges of waves rushing out), 2nd, (kind of like Rachmaninov’s in style) and 3rd concerti, Tovey’s, Ravel LH, Korngold LH, Scriabin, Liszt’s 2nd, Rachmaninov’s 4th, Panderecki, Dvorak, Tchaikovsky’s 2nd, Prokofiev's 3rd. These come readily to mind. I hate to say that R.Strauss’s Burleske has not an impressive ending, it is however a very effective one.