Swiss Airlines offers San Francisco to Budapest at $652 round trip for departures from January into late April. This fare is available on most dates.
Star Alliance partners Lufthansa, United, Austrian offer similar fares. Swiss K class offers 50% flight miles with United Mileage Plus making this the best Star Alliance airline choice for earning redeemable miles in Mileage Plus.
Beware: Lufthansa K class is not a miles earning fare with United Mileage Plus.
SkyTeam Alliance ticket prices are in the $680s flying Delta, Air France and KLM with the same departure date range January to April, and low fares on most dates from January to early March, then Sunday to Thursday departures in March-April.
Swiss Airlines San Francisco SFO – Zurich ZRH – Budapest BUD
$652.15 Tuesday March 8 – Tuesday March 15
Flight miles: SFO-ZRH-BUD-ZRH-SFO = 12,683 miles and 50% miles in United Mileage Plus = 6,341 redeemable miles.