"if' VS "else if"

if(...)
{
}
else if(...)
{
}

is completely equivalent to:

if(...)
{
}
else
   if(...)
   {
   }    

in the same way that:

if(...)
   foo();
else
   bar();

is totally equivalent to:

if(...) foo();
else bar();

It's 100% style, and whether one is more or less readable than another is a total judgment call based on your programming culture, language and how complex the statement is.

I've never had issues debugging 'else if' statements. I think using 'else if' statements are clean and it communicates to a programmer reading the code that the group of 'else if' statements are mutually exclusive.