What was the challenge with Pendragon? I have a Pendragon game currently running here that just passed its 2-year anniversary.
I will admit that the system is a little old-school for me. If I were to run it from scratch, I'd use the ORE system (i.e. Reign). I did a fair amount of work to build a random char generation system for ORE, import passions, and stat the various regional powers of Salisbury as ORE companies, before I got "elected" to take over my current Pendragon campaign. I'd be happy to share if you're interested.
(It is worth noting, however, that I don't usually allow PC spellcasters, or at least not without a lot of work and time investment. I do have a sense of how magic works in my game, but it would likely be less flashy than what you might be looking for... no teleporting armies across the map, for example, nor blinding King Lot's armies with a flash of light off Excalibur.)