'Best' would be a Molle vest platform, and then adding your choice of pouches
Then you can reconfigure for the day and how you are going to play, developing and changing over time
But that comes at expense
Molle was very hard to get in the UK, but is easier now and is compatible with osprey
You can mix and match proper military grade Molle, Airsoft and paintball specific pouches
Hong Kong sources such as ebairsoft make your money go further
Cheaper than Molle but not flexible is a dedicated combat vest
Have a look around your local army surplus
Depends what mags your running? If TMC most 556 mag pouches will work. Anything else you'll be best off with OMG pouches though they'll be hard to come by now Magfedpbuk is no more.
For the vest go for a UKtacical one as a base. Expensive for PB but only one you'll ever need. There are a few different types to choose from. If you want to save some money try the classifieds in Zeroin airsoft.
I prefer to use a UKtactical chest rig with OMG pouches.