PHP - concatenate or directly insert variables in string

Between those two syntaxes, you should really choose the one you prefer :-) Personally, I would go with your second solution in such a case (Variable interpolation), which I find easier to both write and read.

The result will be the same; and even if there are performance implications, those won't matter 1.

As a sidenote, so my answer is a bit more complete: the day you'll want to do something like this:

echo "Welcome $names!"; 

PHP will interpret your code as if you were trying to use the $names variable -- which doesn't exist.

That day, you'll need to use {}:

echo "Welcome {$name}s!" 

No need to fallback to concatenations.

Also note that your first syntax:

 echo "Welcome ".$name."!"; 

Could probably be optimized, avoiding concatenations, using:

echo "Welcome ", $name, "!";