Ben,
As long as you buy a PSU from one of the larger, well known brands you should have no issues - most are fairly similar spec wise. The Corsair PSUs are very good (and expensive), but the standard supplied cables are horrible and I have had to replace them on 4 of my PCs (AX1600i, AX1500i, AX1500i, AX1200i) as the insulation is far too rigid and looks really cheap and tacky (noting that I am an Electronics/Avionics Engineer by trade and have been building PCs for family, friends and work mates for the past 27 years).
Seasonic used to (5-6 years ago) provide nice braided cables as standard on their modular PSUs (I have two , a 850W & a 1050W?), but I think this changed in 2015 and they have gone down the same dark 'all black, flat cable' path as Corsair, but their version seems a bit more flexible.
Thermaltake PSUs have always been good VFM and often have useful extras, but I do not have recent experience of their flat black cables.
Enermax used to produce (10+ years ago) an amazing PSU known as the 'Galaxy', these PSUs had the best quality cables I have ever come across on a consumer grade PSU (and far better, in terms of conductor and insulation quality, than any of the 'fancy', expensive custom cables you can currently buy). So good that I repurposed the cables when the PSU died and they live on inside a server!
Based on your system, and allowing for some growth, I would choose a 700-800W modular PSU, or if money is tight go for a fully wired, non-modular unit or part modular unit, which may be +£50 cheaper for the same quality PSU. If you choose these cheaper options, braided cables or truly flexible flat cables become more important as you will need to fold and hide/stow away the unused cables neatly within you case, i.e. with a modular PSU you only fit the cables you need to the PSU and the remainder sit safely in the box until you need them in the future. If your case is small and you have nowhere to stow surplus cables without disrupting the internal airflow a modular PSU is a godsend.
In sum, set your budget and have a good look at the cables which are being offered as standard, i.e. braided cables are easier to route around a case, look neat, but are becoming much harder to find as standard and are less important if the unit is at least semi-modular. Also, do not forget to check the manufacturer's warranty which range from 1 to 10 years! Select a few models within your budget, perhaps starting with a mid-range units (with 5 year warranties) such as an EVGA 750 Watt BQ Semi Modular ATX PSU & Corsair 750W CX750 Bronze ATX Power Supply, and then use google to search for reviews of each one to do a proper comparison.
Regards,
Mart68