Welcome aboard Carmencita!
Fins... this is like asking what's the best car, or best anything. Different strokes for different folks is the rule here. If at all possible, find others in your area where you can try out various fins/styles. Most of the dive shops I've used that have rental gear are more than happy to loan you fins to try out (in hopes you'll buy from them)...
For me, split fins is my fav (Twin Jets)... others feel they can't maneuver, or go fast enough or they feel odd in these so they like conventional fins. Length, color, style, material... not to mention cost, are all a factor to consider.
Shop around at whatever locations you have that sell fins and try some out for fit. Ultimately that's the only way you can be sure something will fit, kind of like shopping for shoes.
Also, you'll want to decide something else before the fins... if you're wearing booties or not, that will definitely have an impact on what fin size/fit to get.
Hope that helps some.. 8^)