Two beautiful destinations in different seas. Corfu is in the Ionian with Venetian architecture and lush landscapes. Halkidiki is in the Aegean with 3 peninsulas and pine forests.
Corfu is wetter (more vegetation). Halkidiki has a drier Mediterranean climate — see the weather guide.
Corfu has rocky beaches in stone coves (Paleokastritsa). Halkidiki has endless sandy beaches — see best of Sithonia.
Halkidiki → 1 hour from Thessaloniki airport, no ferry. Corfu → flight or ferry. See access from Belgrade.
Halkidiki is clearly more affordable. See accommodation prices.
For British-feel and Venetian town → Corfu. For ease, cost, sandy beaches → Halkidiki.