Gable end vs lean to roof

[Mk555blue]

Hi everyone. We’re replacing a leaking flat roof on a small extension and need to decide between a lean to or gable end roof. Cost is mostly the deciding factor, is there a clear winner? Any other things to consider with this that i may not have thought of? thanks. 

[Mr Punter]

Gable might look nicer.  I assume this is single storey onto a 2 storey.  Any windows or awkward bits above?  A photo would help a lot.

[Iceverge]

Pics please.