Bulgaria vs Serbia

Bulgaria's $1,215/mo monthly cost (across 2 scored cities); Serbia's $1,156/mo monthly cost (across 2 scored cities) — not enough data to call a winner.

Bulgaria's 2.6/5 safety score (across 2 scored cities); Serbia's 2.5/5 safety score (across 2 scored cities) — not enough data to call a winner.

Bulgaria's 2.4/5 mobility score (across 2 scored cities); Serbia's 2.1/5 mobility score (across 2 scored cities) — not enough data to call a winner.

Bulgaria's 2.1/5 culture score (across 2 scored cities); Serbia's 3.2/5 culture score (across 2 scored cities) — not enough data to call a winner.

Bulgaria's passport reaches 102 destinations visa-free to Serbia's 91 — Bulgaria opens more doors without a visa. Passport strength shifts over years of naturalisation, not months of planning, so it's a long-horizon footnote — not scored in the tally.

Bulgaria is better connected than Serbia — 12M passengers/yr vs 8.9M passengers/yr. Bulgaria is quieter than 59 of 87 countries worldwide; Serbia is quieter than 65 of 87 countries worldwide. Bulgaria sees ~2 air passengers per resident a year; Serbia sees ~1 air passenger per resident a year — a derived figure, not itself ranked.

Bulgaria runs -12°C to 34°C for most people; Serbia runs -11°C to 37°C for most people. Depends on you — which range fits your tolerance is the real question here, not a score.