How do you define the measure of complexity? If the measure is number of features the Ada, PL/I, or C++ would be near the top of the list. What about the ability to describe the same solution in a huge number of ways? Well, at that point my vote might be for Perl. Lack of clarity? Assemby language takes the crown, but Perl would have a special mention because at times it can resemble line noise. Then there are the huge number of languages that I either have no experience with or didn't bother to mention because they aren't very popular in the mainstream. Comparing languages is an exercise in futility unless you have a specific use in mind.
>So what language you recommend?
PHP is an Algol decendent, just like C, C++, C#, and Java. You would find the syntax of any one of those to be comfortable. However, there is much to be said about Lisp or one of its variants. While you may not use it--ever--you will learn a great deal about programming by learning a language that is so different. If you want to ease into the pool a little bit more slowly, go to C, C++, C#, and Java by way of Python and Perl.
In the end, the choice is yours and you should learn whatever language looks most interesting to you.
