Which software is better, EndNote X5 or Mendeley?

An open source alternative such as Jabref or Bibdesk.

he usado ambas plataformas, no son exactamente iguales, pero si hay que elegir una, prefiero ENDNOTE.

EndNote is great.

One definite advantage that EndNote has is that it is relatively easy to produce new citation styles. In some disciplines (e.g., archeology), every journal has its own particular style for citations and bibliographies, and in EndNote it is fairly easy to create one on demand. This is much more difficult in Zotero or Medeley.

Probably the one you "grew up on." Many of these programs do the same thing but the user interface is different. Having used both of of these applications (along with RefWorks, Zotero, Reference Manager) I will only say that there is often one or two marginal functions that one of them will do and the others will not. Bulk-tagging or bulk edits of multiple references is one that comes to mind.

Fortunately they all "talk" to each other fairly well and therefore using one does not exclude switching platforms at some future date.

Also just to point out that both Reference Manger and Endnote have user forums on the Thomson Reuters site.

Papers.
So far only a Mac software, a Win version is on the way.
Superior PDF management, Paper collections, Cite While YOu Write

I like Endnote. It is a very powerful program, and once you learn how to use it you can do nearly anything relating to references or bibliographies. However - having said that, it is an expensive program, and that makes it difficult to collaborate with people from less wealthy countries. Mendeley and Zotero are less powerful, but make collaboration much simpler. Depends on what you consider important I suppose...

I can only speak for outstanding customer service and support from EndNote. I would not change.

dependes on your style of researching, I like to use endnote and mendley

How about Citavi? The latest version is finally available in English and it is extremely comfortable, offering the same cwyw-features as EndNote plus the extremely helpful possibility to collect your citations, thoughts, resumes ecc. 'behind' the reference software. Does not work under Mac OS though (but Parallels helps).

If the choice is just between EndNote and Mendeley, I'd go for EndNote.

I have not used endnot or mendeley
I have used refworks. Once you get to know of the intricacies of the program, it works very well. our librarian is introducing 2 additional programs that I will pass on info about once I have it.