I would agree that Rab are probably the best on the market. However other good options (and slightly more affordable) are Mountain Equipment, Mountain Hardware and Marmot - a few years back this was the make of choice for many Apline Guides.
I have the Rab Summit jacket and cannot fault it, whilst the wife has the Mountain Equipment down jacket (cannot be arrsed to go and dig it out to find out what it is called) which she rates very highly. They do a blokes version.
Both were bought for a trip to Canada in mid winter and performed very well.
It really does depend on where you are planning to wear the jacket! You will die of heat exhaustion in a Mountain Hardware Annapurna or RAB Summit in the Lake district even in the harshest winter (unless you are planning on bird watching or somesuch), on the other hand either of these jackets are essential wear in Scotland or Alpine region, both are incidentally stunning jackets in both performance and comfort.
Both RAB and Mountain Hardware are quality gear, used by professional mountaineers all over the world (and many amateurs like me) Personally I think RAB have the upperhand purely because of their range of fills - weight and mix of duck and goose. I've had a RAB Glacier Jacket for 6 years, it's been all over and is still brilliant but not really suitable for Alpine wear; more like UK winters and skiing. I wouldn't use any other sleeping bag than RAB - but then again I spent over Â£600 on the one I have!
Don't rule out Mountain Equipment, yes they have branched out into the "leisure/fashion" sectors and some of this kit is just that - fashion not practical unless you are going to Sainsbury but they do still have specialist mountain gear. If you are spending around Â£230 on a decent down jacket you can't go wrong with any of these companies, it will come down to fit - I find RAB a little tight across the shoulders and quite short resulting in me getting a larger size than I would normally in other kit.
This is why TNF have been giving freebie gear to any TV reporter who will wear their jackets. The BBC always used to buy Mountain Equipment.
Alpkit have been getting a good name recently but it depends how much you want to pay. I bought a "Rolling Clouds" jacket from Field & Trek and its still giving brilliant service after many years hard use.