I've raised some rare breeds. Standard chinchilla, belgian hare, harlequin, argente brun... Standard chinchillas are cool, beautiful fur, not much in the way of meat though and sort of, imo, a bit boring. Great history behind them too. Not bad little rabbits. Belgian hares were a mess. To be honest, the lines in the US are not super healthy (read: probably the least healthy breed in the US), and not good quality compared to european hares. They're one of the breeds that has to be raised on solid floors; not something I'd want to deal with. That's a breed that's cool to look at, maybe to have one pet, but not to breed. Harlequins were absolutely amazing. Gorgeous rabbits, healthy, great mothering & litter size, good growth rate. The biggest problem is their markings; probably a majority of the kits have marking DQs, and the ones that don't aren't even that good. Probably only 1/10 will be 'show quality' and even then will never be good enough for anything above breed. For showing, you need lots of room and cages to get a big enough number of rabbits to produce great harlequins (magpies and easier than japanese btw, because then you don't have to worry about white spots). The argente brun were boring, not super friendly. Terrible sprayers (the bucks). If I wanted an argente, I'd just get a champagne and go for the good growth rate; argente brun aren't really in danger of extinction like some other rare breeds, they're more rare just because they're new.
Edit: in case you can't tell, I'm partial to marked breeds :lol:
Another edit: and belgian hares are expensive little things! $100 was what pet quality standard ones were going for when I was looking, and that wasn't even at nationals.