I have used many portable servers, but nothing compares to Joomlas2go (J2G) for Joomla web development. I was pleasantly surprised when I first started using J2G how everything was configured for Joomla, and how easy and intuitive it was. Now I can port all my Joomla websites to showcase to my clients, and it's worked on every computer I've tried it on. It definitely cuts off hours of my development time. The developer at J2G was quick to respond to my request for support, and he gave very detailed instructions on how to get unstuck.
If you're serious about Joomla development, don't waste your time (with free or paid extensions) with what's out there. J2G has been a blessing, and I use it everyday in all my work.