Jim's got a few years experience on me working dogs, but i do get out and about a far bit with mine working them on shoots, i have seen all sorts of breeds and half breeds on shoots some good some not so good.
My dogs have found birds missed by FTCH of various breeds numerous times as they have done the same to my dogs many times and i've seen some truely s//t dogs (in my opinion) find game that mine and other dogs have missed. There is a fair bit of luck involved dependng on scenting conditions as well as various other things, but some dogs are luckier than most. I once seen a yapppy litle terrier literally break free from its lead to retrieve (well sort off) a well maked grouse behind the butts, there must off been 20+ dogs off all breeds over the area trying to find that grouse inc a few with ftw/or red letters. Was almost perfect until it bagan to shake it as only a terrier can
that doesn't make the terrier a better dog or breed. Work ur dogs long enough on shoots u will lose birds get 'eyewiped' and 'eyewipe' others, just got to hope u and ur dogs do more off the wiping in the long term
I will say ur choice dog breed is a very personal thing and its good that everyone has different opinions, be very boring if all the same breeds out in the field, and quite often the opinions are very strong
My biggest critism would be just be honest the op is asking advice that is going to influence possibly the next 10+years of his life.
U have a 6 month old pup which is ur first gundog, things are going great but far far too early to really say how it will turn out, how can u prefer 1 breed of working dog to another when u have only worked 1 breed (and in actual fact haven't even worked that breed yet), u have no idea wot other breeds can do or even wot ur own breed can actually do or wot it's limitations actually are.
For the op i'd contact the working or breed societies possibly even get along to training days or Field trails to see them in action and make ur own mind up if it's wot u want.
All i'll say is there rare for a reason. If u compared it to buying a car, a springer or lab would be like buying a ford or toyota yes may be boring and common but do the job very very well with no drama's, for a first (or any) gundog that is exactly wot u want
Try phoneing and asking a few off ur local pro gundog trainers about lessons, many won't take in 'novelty' breeds for training or 1-1 lessons
Just to make things interesting i actually disagree with jim above
i think the lab (althou only proper old fashioned lines that actually hunt and hit cover) is a far more rounded versatile shooting dog in my opinion but that is my preference as labs tend to handle water and cold better purely due to there coat, but i have swept ground for birds when my springer has missed them and a lab has found and vice versa, i actually think a mix of each is the ideal as they seem to scent in slightly different ways. And quite often keepers or serious pickers up will have a mix of breeds, even a few serious FT boys still have a mix in there 'working' dogs
But i also know folk who would argue till the cows came home an HPR is the best, but there just being really silly
(and i do have an hpr before the hpr boys string me up) His first retrieve was a teal missed by my other 3, actyally quite a hard find, he's 30ish month now and the juries still out on him and the breed as far as i'm concerned, so i think u may be slightly premature to judge a breed at 6 month