Finding the right jacket should be an easy process, especially with the internet at your disposal.
Firstly, what do you want the jacket to do ?.
Do you want it to be suitable for the winter, or just for the warmer months.
If its a four seasons jacket you want, then discount the lightweight models, more designed for the warmer weather, if you hang up your boots come October, ignore the expensive four season waterproofs.
The four season jackets, usually cost the most money, and have the best gadgets and facilities on offer.
A lightweight warmer weather jacket, are usually more affordable, and have fewer thrills, but are usually totally unsuitable for sub zero winter temperatures.
Secondly, how much can you afford ?, if money is not really an issue, visit the websites of The North Face, Berghaus, Mountain Equipment, Lowe Alpine and the other top names.
Only you know what you want the jacket to do, the rest should be down to trial and error and hours of internet searching.
Once you have set your budget, select several jackets from the big named retailers, and then if possible, visit a respected retailer, so you can see and try the jackets on.
It will then be down to you, to whittle your choices to maybe one or two jackets.
If money is an issue, as it is for most of us, still whittle your choice down to one or two jackets, and then search high and low for the best possible price.
This is how i chose my waterproof, after knowing exactly what i wanted the jacket for, and how much i wanted to spend.
Before the days of the internet, buying a new 3 or maybe 4 seasons waterproof, was not easy, but with every manufacturer showing their stock on their websites, settling on one specific jacket will be down to trail and error, and how it feels on your shoulders.
Good luck, and start that elusive search for the best waterproof for your requirements.