Most Apistos are about the same size as a ram (There's some variation of course, depending on what species you get). A 29 gallon tank would be the perfect size tank to hold a pair of either apistos or rams. Other than spawning sites, their behavior is pretty similar. There's a few apistos out there that are a bit more aggressive toward each other, but otherwise, care is pretty similar. In a tank that size, you're likely only going to want a single pair. Certain species can be kept as harems, but the females are going to squabble. Contrary to common conjecture, you don't have to have super soft, acidic water.
Rams are usually more easily found locally than most apistos, so unless you want to mail order, I'd suggest going with them. Either fish will be fine with most small, schooling fish. They really are only aggressive towards other cichlids. They'll spend 99% of their time in the bottom half of the tank, so any mid-topwater fish is a good compliment. They aren't shrimp safe by any stretch of the imagination however. I keep amano shrimp with them, but have seen them bite them a few times.
A 29 gallon tank is too small for discus in my opinion.