Jotnar on a team with a couple solid control troops (eg., converter + troll) are among the “safest” guild wars teams I’ve been able to build, but they generally take me playing the board a whole lot and wasting actions to get my mana up and make sure I leave no openings when I finally strike. Ketras needs to go in hard and strike first to be effective, but with the right setup, it is pretty easy to get him to one-shot range by the time he is full mana. I’d put Jotnar as probably more useful in GW, but pretty much only in GW (super slow in PvP, to make use of barriers require you to carefully choose your openings), while I semi-frequently trot out Ketras in PvP (can be fast, uses a color chain that you can deny meta troops with) and also uncommonly in GW (when I want to keep my action count down and score up, and I think the battle can handle it).
(Note: Jotnar is a troop that benefits heavily from trolls and blob matches, because you can actually semi-frequently get a barrier on the entire party through mass trait fires, unlike pre-Unity when this was a very rare occurrence. There has been a lot of discussion on these topics recently. An alteration of the way blob matches work or a nerf on trolls would significantly drop Jotnar’s usefulness, with no guarantee he would ever be addressed again, so keep that in mind. )