I'm not a novice but I am nervous.
I can say I much prefer a forward, responsive horse to a sluggish, half-dead school horse. But - and this is a VERY important but - that ONLY applies if the horse has excellent brakes too! My nerves come from having had some nasty falls off runaways and bolters and therefore I have big problems with horses that don't listen when they're asked to stop.
When starting a horse to saddle I always establish a solid verbal "whoa" on the ground before I get on. I also make sure the horse knows what bit cues mean - turning and stopping - so that I can back up my verbal "whoa" if I need to. So my horses ALWAYS have a good stop on them, if I've trained them from the ground up. And for this reason I have a tendency to prefer horses I've trained myself, though I'm sure I lack the experience to put a foundation on them without leaving holes.
EDIT; though I would very much NOT suggest a nervous novice ride a breaker! Just saying it's not uncommon for nervous riders to actually prefer more forward, more responsive types, AS LONG AS THEY WILL STOP.
MAKORA THOROUGHBRED SPORTHORSES