As I've experimented over the last year, I've found that I prefer my suits to be as unobtrusive as possible - that's likely because in both my work place and personal life, wearing even a conservative, solid navy single-breasted notch lapel suit is a bold statement. I do have a windowpane suit that I got when I was figuring out my personal style - charcoal, worsted, with a faint chalkstripe in white - but I like it much more as a sports coat.
I also have a pinstripe suit and objectively it looks fine but for aesthetic reasons I'm just not a fan of pinstripes - again, I was figuring out my personal style.
But if I had to choose between the two I'd go with pinstripes. Just seems more appropriate for a suit, and will stick out less. But I'd much sooner go for a patterned solid: nailhead, birdseye, pick & pick, etc.