It pains me to say, I have to agree with Gixer's sentiments about choosing the "best" spares for the car. The "best" may not necessarily be the best quality, cheapest, branded, Genuine etc.
As (probably) the biggest Omega-B community in the Universe, we should be well placed to be able to ascertain what are the best options.
The best options are likely to be a blend of Genuine, branded and unbranded pattern, depending on the part concerned. For example, I'd only use Genuine cam cover gaskets, personally I prefer branded tyres such as Dunlop, and bulbs are usually Halfords tat (for convenience - my dealer won't deliver just a handful of bulbs

).
For a battery, I have no brand loyalty. I've had reasonable success with GO batteries. I've yet to find a battery that lasts as well as the one fitted in the factory, which usually lasts 10yrs. I'd personally try a Tradeclub one, or buy branded one from a reputatable supplier with a decent warranty. Keep the receipt, as this is a convenient way for the supplier/manufacturer not to honour the warranty of shite batteries... ...they can offer a 100yr warranty, but not have to honour it as they know the vast majority will loose the receipt.