Servants of Ark2) The First Named -- Jonathan Wylie
12) The Centre of the Circle -- Jonathan Wylie
13) The Mage-Born Child -- Jonathan Wylie
The Unbalanced Earth15) Dreams of Stone -- Jonathan Wylie
17) The Lightless Kingdom -- Jonathan Wylie
19) The Age of Chaos -- Jonathan Wylie
Two trilogies of fairly traditional fantasy. You know, the 'lets go on a journey and have our major characters go on a journey inside their heads at the same time' type. In the Servants trilogy magic is Real and Works, but it's a lot of effort none the less, so it's pretty much only practiced by the one Wizard on each island.
The second trilogy is set in the aftermath of the first; the (main) viewpoint character being one of the minor characters from the former trilogy and the action being in the as before unknown Southern Continent. As such there is little linkage, although Gemma often finds herself being accused for all the things that have gone wrong in the Southern Continent since the Breaking at the end of the first trilogy.
The second trilogy is harder work, and darker; but I'm tempted to prefer it none-the-less. The model of magic in the first trilogy appeals to me more though.