Added subjective ratings for Dancing, Music, Atmosphere, Location
Stars of Salsa
Dancing - 3, Music - 4, Atmosphere - 3, Location - 4
Three awesome dances, I was there only for 2 nights.
Mambo Nights B-day
Dancing - 3, Music - 4, Atmosphere - 5 (because of pre/after parties), Location - 4
Tallinn Salsa Festival
Dancing - 4, Music - 4, Atmosphere - 4, Location - 4
It's hit and miss each year, sometimes better sometimes worse, organizers change often.
Mambo City 5*
Dancing - 3, Music - 4, Atmosphere - 3 (or 4 if rum is counted in, drinking is kinda necessary), Location - 2
Great dancing after 2AM, too many people, not that good band, no air, bad floor, had some mind blowing dances as well - this is London.
Istanbul IDF
Dancing - 4, Music - 4, Atmosphere - 4, Location - 4
Too many shows, bit too Islamic culture, warm and friendly atmosphere, great Turkish people.
Prague Salsa Marathon
Dancing - 3 (few dancers, range of levels), Music 5 (something I experienced only here, great music at meal times, relaxed djs playing for fun, it got worse at prime dancing time, when usual stuff got played), Atmosphere - 5 (most friendly), Location - 5 (great place and Prague was blooming at that time).
Tons of music, great environment, great food included in price, lacked Czech people.
Vilnius Salsa Festival
Dancing - 3, Music - 4, Atmosphere - 5+, Location - 4
So buzzworthy, started losing steps in last day.
Riga Salsa Festival
Dancing - 4, Music - 4, Atmosphere - 5+, Location - 5+
Great atmosphere, little sleep, it's my home town, so atmosphere and location probably get extra point from me, YMMV.
3rd Front reload
Dancing - 5+, Music - 5, Atmosphere - 5+, Location - 5+ (except getting Russian visa, which is expensive).
The only thing this event was missing for me was great live bands.
Bachaturo
Dancing - 4, Music - 4 (it was more radical in salsa room, because it's bachata fest, YMMV), Atmosphere - 3, Location - 4.
Belarusian Salsa festival
Dancing - 4, Music - 4, Atmosphere - 5, Location - 3.
Tiny fests are easier to make great, but they are more volatile. Many locals did not come. Did I say it was tiny?
Berlin Salsa congress
Dancing - 4 (great from 3AM till 7AM), Music - 3 (good in afterparties), Atmosphere - 4 (but you have to take your own people), Location - 2.
Warsaw Salsa Festival
Dancing - 5, Music - 4+ (too much romantica, live bands awesome), Atmosphere - 5, Location - 4.
All around might be better than Rostov, because some people like shows and workshops and live bands. Dance wise Rostov has the highest level. Like Rovinj this festival is getting too big.
Riga Bachata festival
Dancing - 3, Music - 3, Atmosphere - 3, Location - 3 (but it's 10 minutes ride from my house and I had couple great Salsa dances there)
Baltic Fever festival
Dancing - 4 (not enough people on Sunday), Music - 3 (too much romantica), Atmosphere - 4, Location - 5
This fest pleasantly surprised me. I thought it will be mostly bachata, kizomba, but there was dedicated salsa room on all days except Sunday and many good salsa dancers. I even took classes on Saturday.)
Dancing: I like dancers who can, who play with music and myself, improvisation and musicality. I do select my dance partners and over years we start to know each other and it gets better and better. Basically, in larger fests I always have someone good to dance with.
Music: I don't like whiny salsa (romantica), I like surprises, unusual music. Don't like too much bachata (more than 4 per night) and no kizomba please.
Atmosphere is very subjective - half of it really depends on people I know beforehand. But in Prague I did not know anyone beforehand and became friends with quite a few.
Location - is about where events happen, how to get there for me, where to stay and the city in general. I like to go for a hikes in the area in the morning.
I might have forgotten something - probably some nice local events. La Rumbantela monthly in Kaunas is usually very good. I was to several smaller events in Moscow - some where very good. And some very good smaller events in Istanbul, I don't remember names. There was great event in Munich - don't remember name as well. Also sometimes weekly parties in Riga have higher level than some fests above, but that's highly volatile.