What is the best response to 1.c4?

It's really a matter of taste. I'd prefer 1...Nf6. Not only it is the most popular response, it's also very flexible and can easily transpose into a normal 1.d4 opening, like the Queen's Gambit, King's Indian, Nimzo-Indian, and the Queen's Indian. 1...e5 is also a popular choice and is very good, as it directly occupies the center. 1...e6 is also playable and can transpose into 1.d4 Nf6 2.c4 e6 openings. 1...c5 results in the Symmetrical English and is another option. Other moves aren't as good, so I wouldn't recommend them.

I gradually took up the English for the same reason I took up the Sicilian. I hated facing them...

I find that most of the time black plays 1...e5 and I think this is good. I play ...b6 systems against it which seems to give good chances and white won't be so familiar with as 1...e5.

I think symmetrical systems with an early ...e6 look good...

Define "best." If you want to draw, 1...c5 is "best"; if you want to win, probably 1...e5 is "best"; if you want to be noncommittal, 1...Nf6 is probably "best".

http://www.chess.com/forum/view/chess-openings/suggestions-against-1-c4

You need to be ready for this but it's not unplayable for black. 

As for the original question there is no "best" response.  The English is a flexible opening and black has numerous options which are pretty much equally good. 

I prefer C5 for the simple reason that I prevent my opponent advancing a further rank by the opening pawn. If this happens it immediately puts me under pressure and defensive mode. So i obstruct with C5.

e5, c5 and Nf6 would all be good, although all very different. d5 would not be so good because it would gift white a 2-vs-1 central pawn majority after the simple cxd5.

1.. e5 is the best.

Jump up and down and spit wooden nickels.

I like to play 1.c4 and 1...e5 scares me the most

I usually play c6 and hope to go into either a Caro-Kann or a Slav, both defenses that I'm more comfortable with.

hope chess is bad chess

True but 1...c6 is fine against the English.  As is 1...e6.

Well it's not like they have many options...

White certainly doesn't have to tranpose to 1. d4 or 1. e4 lines.  Actually white has quite a few options the English is a flexible opening.

Well other "responses" I can still get to develop Caro-Kann style so that's ok by me

If it weren't for 1... e5 I'd play the English all the time. I just don't think White get anything out of this line, and it may end up with Black having a bit of an advantage.

I will say how I play against it, and what gives me the most trouble when I play it as white. I personally respond with g6 with the intent of developing into a King's Indian, the same as if they opened d4. My experience when playing as white is that Black gives me the most trouble when responding with e5 (which is what they normally do). c5 is the response I enjoy seeing my opponent play the most.

White will push the d pawn at least one space in this opening, and e5 means white must be prepared to deal with the Black's dark bishop able to put pressure on either the a5-e1 diagonal, or pressure on f2, either one of which can be supported by the Queen. Castling alleviates this (or a3 depending on the situation), but it takes an extra move or two, during which time black can continue to develop.

This could also be true if Black plays e6, which they can use to develop into a Nizmo-Indian, which I think is also a fairly good response.

When black plays c5, it always seems to let me develop easier when I'm playing the White pieces in the English.

Someone here responsded with black playing f5. An interesting chioce, and I can see some advantages, but I personally HATE moving my f-pawn, whether white or black, in the opening.

For anyone who plays the Sicilian seeing 1. c5 e5 should be pretty good news since you're effectively playing the Sicilian with an extra tempo.

Give him the rasberries