Which is better for double-sided printing - 14pt or 16pt?

Both handle double-sided (4/4) printing without any trouble. Neither stock suffers from show-through with standard CMYK printing, so your choice comes down to feel and budget rather than print quality. The only edge case is very heavy ink coverage on both sides, where the thicker stock offers a bit more opacity.

• 14pt: prints double-sided cleanly and performs well for the vast majority of designs.
• 16pt: slightly more opacity, useful when both sides are packed with dark, heavy coverage.
• Neither shows meaningful ghosting or bleed-through with normal ink levels.
• Decide based on the weight and finish you want, not on double-sided performance.