Regardless of the fish, you should ask yourself are you prepared for the commitment both species require. Both MUCH more water than most people ever give them, and both will live a decade or two.
The hard truth is most people are not ever really prepared to keep such species. Many of us who have kept some of these large types of fish have come to realize they aren't really aquarium fish in the normal sense. They need far more space than almost anyone is going to provide.
To answer your questions:
1. Which Grows at a fast rate.
Both will grow quickly in a good situation. Less a function of species and more one of situation.
2. Which one has more personality and out going
Neither will be outgoing on the level of many other cichlids (Midas, etc.) until they are fairly large. They can, in fact, be shy when young.
3. Which bangs on the glass more
Glass banging is a pathological reaction to extreme isolation in a stimulus poor environment. It is not a natural behavior for a non-breeding fish (just as many of the behaviors seen in zoo animals are not natural or indicative of a healthy animal). I don't believe it is a good goal to hope one's fish behaves as do some of the crazies we've all seen. It is easy to provide a healthier environment by making sure fish are kept in mixed tanks wherever possible. That said, both are highly intelligent and will come to recognize and interact with their owners as they grow older. In a fry guarding situation, both are very aggressive toward anything, and I've had dovii makes that were about as aggressive as any fish I've ever come across (of course, their size makes their displays more fearsome appearing).
4. Which Eats more
Both will have similar requirements. A large fish will only need to be fed every few days or so.
5. Which is mroe aggressive towards other fish
I have successfully maintained large male dovii with other fish several times, but in a small tank (i.e. anything under several hundred gallons) you can expect carnage. The same could be said for umbees. The key is keeping them with fish all their lives in a suitably sized system. As long as they have space to breed and feed naturally, they will coexist just fine with many species of fish. Crowded, and you will have trouble (but that is the same case with most CA cichlids; it's just that the much larger dovii and umbee exacerbates things).
By the way, I'd be wary about taking advice from people who've never owned either. I'd be even MORE wary about taking advice from people who've only owned small ones....... There's a reason you see lots of little ones and very few big ones. I know of only a handful that have grown either to anything close to fully grown, and none of those people would be likely to suggest them as pets.
umbee hands down!!!
