My visit to those 3 cities (BTW Vienna should be visited between the other two to save time on transportation and avoid backtracking) was in mid-May. It wasn't really cold anywhere, but it was grey and very rainy in Budapest, grey and drizzly in Vienna until my last morning, and sunny in Prague. Much as I enjoyed Budapest and Vienna, the weather substantially detracted from the experience. I returned to Vienna last year in June and it was so much better, especially since the gardens were in bloom, and Vienna has several wonderful gardens in the centre.
On the other hand, Andalusia is the warmest, driest part of Europe. I've been twice, both times in February, and loved it. Barcelona too. Note that though they share a long border, transportation links between Spain and Portugal are sparse and slow. It's not easy to see both on one trip and there's enough in Spain to fill up your time and a very good high-speed train system.
Data for March 7:
Prague sunrise 6.33; sunset 5.55, day length 11 H 22M
Budapest sunrise 6.12; sunset 5.38, day length 11 H 25M
Sevilla sunrise 7.46; sunset 7.24, day length 11 H 37M
Barcelona sunrise 7.16; sunset 6.49, day length 11 H 33M
So while the length of the days is almost the same, unless you are really early risers, you'll have more daylight sightseeing time in Spain.