I have a K&M cob GP saddle for my youngster - I like it because I can change the headplate as he grows and muscles up. It's also very comfy.
My friend has the cob+ for her mare - similar to cob but with closer contact panels, she likes that too.
K&M also don't seem to be expensive compared with other leather saddles - I paid £670 for mine new.
I have a K & M jump saddle for my new boy. Really nice saddle, fits well but the main reason i went for it was because it is adjustable as my horse is still growing and filling out. They are the same as the Thorowgood saddles but leather.
Dont no much about Black county saddles so cant compare.
I would get the saddler up with different saddles and see what fits him and you both, you might find one brand better than the other.
I have a K&M jump saddle and really like it. My saddler is very picky (she is president of Master Saddlers Association, so knows her stuff) and really rates them. Good price, well designed and really adjustable- would definitely reccomend. (although she also reccomends the Black Country saddles, so they must be good too. It's just they were more expensive and less adjustable, so I went with the K&M)
I have a Kent and Masters GP saddle and i have to say I do love it too.. Very good value for money and it's great as you can change the gullet, which i have done already in owningit for 5months!