hello.. does anyone know which one is bach's easiest fugue? thank you

I'll reply to this by saying that "easiest" is a bit slippery of a term. In general, what makes the fugues of Bach (in the WTC) difficult IMO are the muscal and structural complexities, especially when played on a piano, which allows for the performer to also be conductor to the voices, managing their levels of prominence, allowing for distinct traits for each voice, not just each hand. If we accept this as a basic premise, I would have to say that the Fugue in E-minor of Bk 1, which is uncharacteristically only in two voices, is your best candidate as it is really more an (2-Part) Invention than a fugue, so would represent earlier stages of development of the musician. If you wanted a bona fide fugue that isn't too difficult, I would recommend the G Minor of Bk 1. It also has a lovely Prelude paired with it.

Let us know what you try!
Eddy

Personally I found that E minor fugue to be a little awkward--it's not quite as easy as it looks. I think there are three voiced fugues that are easier (depending, as Eddy says, on your definition of "easy"). As well as the WTC, there are plenty of other fugues worth looking at. You might like to try the last movement of the toccata in E minor: it's a little longer, but lies under the hands quite nicely.

I'm always suspicious of people looking for "easy" music What is your reason for asking?

I would add that some of the 4-part ones are easier than some of the 3-part ones: I am thinking of book one in g.

IMO the C major fugue BWV 952 is one of the simplest ones Bach wrote. Not that it is exactly easy, requiring good facility and careful fingering.
But that is ok, fugues should not be easy

I've been working on the E minor from Bk. 1. That one is deceptive. There are subtle changes here and there that require slightly different fingerings (and woe to the one who puts the wrong finger in the wrong place at the wrong time). I even have them marked in LARGE numbers in my score to help jog my memory, but by the time I remember why I wrote them there in that way, I'm at the next subject entry.

Haha, I used to pencil big exclamation marks, and "Sic !" in my scores. More often than not, I could afterwards not fathom out what they were about. I've now found that it is better to be more specific

The fugue in c minor from Book I is also relatively easy.

That is one of the easiest Fugue that I know. But you can also try the Fugue from Prelude and Fugue No. 2 in C Minor (WTC I), which is considered one of the easier three voice fugues.