Revamping Wordpress Blogs

My wordress blog theme has limitations. It isn't mobile ready, I can't switch themes or use multiple themes, I can't switch templates or assign templates to pages, I can't apply styles specifically in any way ti anything, the header is not dynamic and on and on... This blog is indispensable? to everything I do and of great use to me, and I've found creative (crappy fixes that handcuff me in other areas) ways around it's limitations, but it really just sucks. I would just like to get more out of it, with wordpress or some other cms like joomla.? I need advice on the merits and price of doing it either way and then I need to do it asap.? ## Deliverables This is a soft adult site.