Dale has some very sensible questions that you do need to answer but I'd also strongly recommend trying them each out in your local camera shop. The A77 viewfinder does take some getting used to. It's a clever piece of kit (focus peaking is particularly amazing) but not for everyone.
To be totally honest, a play in a camera shop doesn't really give you a proper chance to *understand* the camera, so consider buying both online. Under the distance selling act you have 7 days to return it so a good chance to play with each. Alternatively your high street store may well offer a similar option.
