most people will tell you that bronze, peppered and trillis are the easiest to breed but there is no reason why any cory shouldnt spawn if they are happy and looked after and given a good variety of food etc. i was in lfs earlier and saw some really nice adolfi corys which i was very tempted with... still am actually but i was on a discus mission so left them!
its totally down to the fish as individuals as they want to spawn and also depends on what sex fish you get. they are similar but the female will be wider and slightly longer but if they are young fish its hard to tell, there is no colour or marking differences and of course you can only have what you can get your hands on. but with a group chances are there will be a mix in it but not guarenteed.
there are loads of nice corys out there it just depends on whats available to you. if you have a maidenhead near you (if in the UK?) then they seem to be getting more species of corydoras in lately.
keep us informed on your choices
at pets at home your probably limited to bronze and peppered but if ordering online you can probably get pretty much anything you want so the choice is endless.....
a few of my favorites for you to check out are peru gold stripe CW10, peru green stripe CW09, black schwartzei, adolfi too many to choose from but its a start
cory prices seem to have risen recently too so some can demand quite high prices im affraid at the minute.....
Well all my cories are cute and i adore them all,but i think the most amusing and cheeky ones has got to be the pandas,they are so like naughty little pups up to mischief and they are easy to obtain.
But has matt says if your are looking for something different then the gold stripes and blacks to name a few are awesome looking fish. they're more expensive than the bronze,albino,tri's peppers etc but it depends where you get them