I'd say get what you can afford. Sounds simple but folks could tell you to get a certain filter because it's the best but it's out of your budget. If you're considering an FX4, I'd say you don't really have a budget issue
So.....most here would prefer 2 filters for redundancy and for Mbuna anyway, stocking can get pretty heavy so more filtration the better. An FX4 would do just fine alone in that size tank and if you have extra filters hanging around (like most crazy fish people do
) than you can have a temporary replacement should something go wrong. Others hopefully will chime in too with their preference. Wavemakers, to me, are a personal decision. If your filter output creates enough water movement then you really don't need it. I use spray bars for surface agitation so I have no real circulation in the tanks. I use Aqueon pumps to get that movement. Again others will have their own ideas.