You can't go wrong with a Bach Prelude and Fugue.
True, maybe Bach's Prelude and Fugue BWV846 and 847.
Gershwin's Preludes and Prokofiev's Suggestions Diabolique are fine and from the 20th century .A Chopin Etude is an excellent choice as well, each of them under 5 minutes. You could even do two or three of the etudes under five minutes .Good combinations:Etude Op.25 No.9 Etude Op.10 No.12Etude Op.10 No.5 Etude Op.25 No.12Etude Op.25 No.2 These are just examples. You could even do Rachmaninoff's Moment Musicaux Op.16 No.4.
Bach Prelude and Fugue BWV847Mozart Piano Sonatas K284, K330, andK333 (1st mvts)Chopin Etudes Op.25 No.12 and Op.10 No.12"Ode to the Yellow River"Rachmaninoff Moment Musicaux Op.16 No.4
You really like suggesting pieces you're learning, don't you?