i planning to buy a smartphone to replace my iphone 4 while waiting for iphone 5

i hv a budget between rm500~rm700 max , considering buying either of xperia u/p/sola/go ......the price are almost the same , but duno what is the different for those phone....especially xperia u/sola/go <--- this 3 phone price is almost the same , rm5xx~6xx for AP

1st question is , what is the different between u/p/sola/go ?....i means performance wise...

my main concern is the performance and battery capacity/battery consumption , previously i used HTC One V before.....this phone is very very slow , does that xperia u/sola/go slightly faster or very fast or slower than One V or almost the same performance ?

my another concern is GPS , i'm a regular WAZE user......is it the xperia u/sola/go able to run WAZE with accurate location pointing ?

please help me decide between xperia u/p/sola/go or recommend other brand with similar price , i'm going to buy one of that phone by today.....cos really need to use WAZE badly to avoid speed trap & road guidance....

a million thanks.....

obviously ace 2