After months of studying pronunciation, I am still not to the point where I can usually tell where a Spanish speaker is from by listening to their speech. I think most of us native English speakers are deaf to the differences for quite awhile.   The differences between the accents from Mexico, Colombia, Venezuela, Costa Rica and even Panama are not marked enough for me to reliably distinguish between and I do not have a favorite among them. I think the accent from Mexico is the easiest for me only because I watch a lot of Univision television and listen to a radio station with Mexican announcers, so it is the accent I am exposed to the most I can now recognize an Argentine accent and an accent of a person from Spain.  Those accents are harder for me to understand than the more Central American accents.  The hardest accent for me to understand is the Cuban accent or any of those others that seem to reduce the ¨s¨ a lot. 

I studied abroad in Seville, Spain and am in love with the Andalucian accent! It can be very hard to understand from a native English speaker's perspective, but I enjoy the challenge. :) 

I don't have problems understanding other Spanish accents but  from Chile  sometimes which is a bit faster. And yeah sometimes I find them very different.  To be honest I love all kind of  Spanish accents I find them pretty sexy XD in special from Spain, Colombia, Venezuela and Argentina.

I am a Spaniard myself. The accents are very different in all the different countries and even inside the countries. But there something very easy to catch. Everywhere except in most of Spain words like "cena", "cenizo", "cima" are pronounced like "sena", "seniso", "sima". Probably it is not original Spanish because these two words "sima" and "cima" means opposite concepts, but they are pronounced exactly identical in most of the Latin American Countries and in some parts of Spain. Besides, most of Latin America pronunciation is softer and more musical than that of Spain. In the south West of Spain: Cádiz, and some people in Sevilla, there is, however, a very funny and musical accent that makes you happy when listening to it.