I'm just gonna be blunt and say it, but people, please do your research BEFORE posting advice to someone completely new to a family of fish that has over 3000 species within it. The family cichlidae is one of, if not THE most diverse families of animalsin the entire animal kingdom. They spread over 5 of the 7 continents even. While no, most commonly available mbuna are not going to be a good fit for a 3 foot tank, there are still dozens of options, and while the OP may say they don't like dwarves, the average fish keeper knows usually of only a small handful of dwarves, mostly rams and a couple apistogramma species at best. There are over 60 species of apisto species, with dozens more that are yet to be described and named, or even discovered! Outside of that fact, you have DOZENS of genera of dwarf cichlids, like ivannacara, nannacara, laetacara, dicrossus, pelvicachromis (like Wy was talking about, and kribs are one of the less colorful species IMO, take a look at p. taeniatus 'nigerian red' and tell me they aren't gorgeous!), lamprologus, neolamprologus, telocichla, some crenicichla even. Need I go on? There are far more than just 2 options at hand. Like I said, research the topic, the respond. It'll save a lot of frustration and arguing.
As for the tanganyikan idea, paracyprichromis are NOT suitable for a 30 gallon, let alone a 75 or even 90. Paracyps are not only incredibly hard to find and ridiculously expensive, but they are very difficult to maintain. Tanganyikan gobies of either of their two genera (eretmodus and tanganicodus) are also generally hard to find).
As for personality, to settle this debate, yes, new worlds TYPICALLY exhibit a higher level of intelligence, thus showing a more developed personality. The larger species are generally carnivores, and thus need to plan attacks and ways to eat, where as most mbuna are herbivorous algae grazers and do not need to have the intelligence as much, other than to evade predators, like clawless otters and cormorants. They do exhibit a much different social behavior though. Again, this is speaking in generalities and is not the same across the board for either continents.
So basically, research is key people. Don't advise someone on a subject you do not thoroughly understand yourself. I am in no way questioning anyone's knowledge, intelligence, or integrity, but rather posting a challenge to everyone. Spend some time learning more about a subject before you try to teach it to someone else. While much of the time, I speak (or write, if you will) from memory, I almost ALWAYS have a google tab open to search something I'm a bit fuzzy on, or something I know I'm not well versed enough in. This forum will continue to lose its more seasoned members if we do not resolve issues like this.