You don't have to match anything, so it's really just a case of what it costs and what you get for that cost.
Ultimately, all cards of the same range (for example an R9 280X at 850Mhz vs 1Ghz) are going to be fairly similar in ultimate gaming performance, though obviously if you can get a faster one for a similar price, it might well be worth the cost.
There are a lot of factors to consider; clock speed, memory speed, memory size, cooler style, cooler effectiveness, noise levels and bundled freebies but cost will be the most significant of all.
Singling out the GTX760 as its one you mentioned, but the method applies to any model of graphics card really. Here is a list of GTX760s on sale in the UK, sorted by price.
http://uk.pcpartpicker.com/parts/video-card/#sort=a6&qq=1&c=142
At a glance, the MSI one at the top of the list is £10 cheaper than anything else, and has a respectably average clock speed. It would seem like a good buy, and it is.
The potential downside is that it comes with a "reference" cooler, a basic design which Nvidia employs, not a bespoke one from the manufacturer. Unlike a lot of cards where normal fans sit on top and blow air onto the board, this type sucks air in at the end, and pushes it through and out of the back of your case. It's quite efficient, and beneficial in smaller cases, but its fairly cheap and can mean cards run hotter and noisier.
The cheapest card with a bespoke cooler is the Asus one, at £195. Its £15 more expensive than the MSI, and no faster on paper, but from the reviews I've read, that cooler is both effective and quiet.
Whether or not you feel that (potentially) spending extra on something like that is worth it is up to you really, in some cases the price difference won't be that big.
As a general rule I'd advise shopping nearer the bottom of the price window than the top, as it's just not giving you value for money, but checking out reviews of any card that interests you is well worth a few minutes of your time.
ijintheuk :
Also, how 'future proof' would you say this PC is? I know it wouldn't be able to run Ultra settings on games in 1 or 2 years time but will it be able to still run games better looking than the PS4 for the lifetime of the PS4? I only ask as I am looking for something to last me a while and I am hopefully going to university next year so will not be able to spend money on any upgrades for a few years.
Nothing is future proof, it's kinda a myth. Comparisons to consoles are tricky as they often have limited framerates, resolutions and detail levels (no Antialiasing, that kind of thing) so PC games will always be more demanding and look better. The PS3 lasted 7 years until it was replaced, the Xbox360 8. Nobody can predict how long the PS4 gen will last, or how a PC will measure up to it. A gaming PC is always on a declining scale, so you can't expect that in X amount of years it will be equally effective as it is today, but the types of machines listed above will still be perfectly capable gaming machines for 2-3years minimum. Much further than that is a lot of guesswork, I'd assume that even 5years or so down the line you'll be able to run modern games at lowered settings (I have an old Core 2 Quad Q6600 paired with an 8800GT both of which launched in 2007, its not my gaming machine but there aren't many things it literally cannot run, though that list is rapidly increasing now)