Definitely Puerto Rico and Cuba! All other countries I have been to have more cumbia type music, some more and some less.
Lockstep has just started a thread about Cuba, you might want to follow that. There was something about Cuba a while ago, search the salsa forum a bit.
Puerto Rico - la isla del encanto
My absolutely favorite salsa country is Puerto Rico.
Check out this link: http://www.abailarsalsa.tk/ and click on Actividades to get a taste what is going on at the moment (if you can read some Spanish). You can sign up for their newsletter so you always know what is going on (and suffer if you cannot go there :headwall. When seeing the concert prices for New Year's Eve dances, keep in mind that those are special New Year's Eve prices, usually they charge around 20$ for those type of concerts, sometimes with several famous live bands. At the fiestas patronales all year around you can see those bands for free: Gilberto Santa Rosa, El Gran Combo, La Sonora Ponceña, Tito Nieves, El Canario, Bobby Valentín, Luisito Carrión, Domingo Quiñones, Tommy Olivencia and I could go on and on...
SurfSalsa and I have discussed salsa in PR in another thread earlier this year, don't remember the thread, something about salsa places in the Caribbean or similar.
Mexico is definitely not a country for salsa dancing, they have a lot of typical Mexican music and dance performances, and in the clubs they play what they call "tropical", a cumbia type of music.
In Costa Rica they play and dance salsa but you cannot compare it with PR or Cuba. I hear all the time that Panama is good for salsa but I have not been there. Several Puerto Rican friends who lived in Panama told me.
Venezuela has some salsa, but certainly not comparable. Colombia has a lot of salsa, I hear, have not been there myself. However, it depends what type of salsa you are looking for. In Central and South America they usually do neither dance on2 nor do they do CLB style or any fancy style, it is mostly basic step to the left and right on1 plus a few basic turns. Please correct me if my info is completely outdated, that is my experience from my trips to those countries a couple of years ago (before the "on2 era"). I have not been to Colombia but have danced with many Colombians over the years.
I'm also living in austria... although I live on Wien (Vienna for the english speakers amongst us..) - never been to graz dancing, can you recommend a club that's good for LA stylers? I've met a guy from graz a couple of times by the name of Dado, and his wife Conny. Their dancing was very good, and we have a few good teachers here in wien (Suzi and Vincent and Dodi), but the dancers here are (unfortunately for me) mostly Cuban style.
I know Conny & Dado they have also a Webside for information, when is the next Dance culbbing in Graz, The adress is salsastic and at. There are the local descriptions: Andino: (Fr, Sa) Alte Postrasse/lillienthalgasse for all Styles, Choibar: Glaccistr/Leonhardstr with gratis Dancecourses (MO,So) starts at 20.00, Rudolf : Am Ender der Eggenberger Allee (We) starts at 20.00 with gratis Dancecourses, Havanna: Beethofenstr 29 (THi-Sa)