Angels and silver dollars are fine together; I keep them together and there's never a problem. I wouldn't personally keep kissing gouramis with either of those fish, though. Kissers get pretty large and territorial. They'd definitely not be a good match with angels (angels and gouramis dont get along that well, and with a gourami that size, both fish would be in danger, imo). The kisser might leave the silver dollars alone, but I've heard reports of kissing gouramis who like to suck onto the sides of slow moving, laterally compressed fish (yes, I know silver dollars can really boot it around the tank, but they spend a lot of time fairly stationary). I should say I've never kept kissing gouramis personally and my opaline gouramis have no interest in my silver dollars whatsoever, so maybe they'd be alright.