Basically, my question is about where anchor tag links should be located.
In the specific sentence Click here to go to this site, what makes the most sense?
Click here to go to this site.
Click here to go to this site.
Click here to go to this site.
Click here to go to this site.
Which provides the best user experience?
Your question is complicated in that it's embedded in a bad practice.
This Smashing Magazine article about why your links should never say "Click here" sums it up quite well.
"Click" puts too much emphasis on mouse mechanics, "here" conceals what is being clicked, and in your example, "go to" is implicit in the action of a link.
Assuming for the sake of example that the "here" you're talking about is Smashing Magazine, applying this approach, your link should be:
Just as a button in a UI wouldn't say "Click here to download" (but rather "Download"), anchor text should function similarly.
Broadly put, your anchor text should comprise of the words that most concisely and meaningfully describe the location on the other side of the link.
Another reason to make your anchor text those words that convey the most meaning, is that the anchor text is a key factor considered by search engines when indexing and determining how to rank pages.
The implications of this for the web as a whole are perhaps too complex to discuss here, but even thinking about this purely selfishly, using anchor text best practices (like I did just there) for your internal linking can really benefit your site.
In the very basic example of a link to a products page, the link:
When you're done comparing, you can view the rest of our products."
is better for everyone involved, when compared to:
When you're done comparing, click here to view the rest our products.
Comments on this answer raise the issue of extreme edge cases in which a user is unfamiliar with the concept of a link, turning the text "Click here" into a helpful instruction.
As edge as those cases may be, I think the point to take away is that there's more to anchor text than just the words. Over-designed or unconventionally styled links are likely to lead to usability issues and detract from a good experience.
Also, this article on making accessible links makes for interesting reading, and goes to show that in a conversation about anchor text and good experience (for most users) the specific words used are only one part of the story.
Adequate, the word "here" is representing exactly where the user can click
Inadequate, you are telling the user that click in a place but the action is located elsewhere
Is a mix between #1 and #2, but is not common. There is generally a one to one relationship between a link and an action. I'd avoid it.
Most adequate, because you are giving a bigger area to do what is intended to do, going to the site.
