Nissan march Or Toyota will Cypha

I would choose the Toyota , as the march is known for rust under the firewall and timing chain issues

toyota make sure it has had propper oil changes easy way to check is look in oil filler if it lookes glazed like somone has baked a cake in a oven shut bonnet and walk away also service records if they produce clean service history to what date.
Nissan is out of these 2 toyota only the newer the toyota the more crap it will also be.

Choosing specifically only between those two cars my call would be the Will Cypha.
Mechanically they are a Vitz so good engine/drive train. One generation newer engine technology than the Nissan evn though the Nissan is chronologically newer.
The funky looks makes the will cheaper than it should be IMO
an equivilant vitz would be around 7k

Pros and cons- the Will Cypha has the better drivetrain without doubt, and probably a wee bit better feel to the build quality too. It's also cheaper, but then, it's older, too. However- the March is a 2007, a nicer colour, and a fresh import. Downside to the Cypha is it's by far a less popular model amongst second time around buyers- and therefore harder to sell (likely, anyway) when you come to move it on. It's also a wee bit harder to source trim and panel stuff for on the cheap- you may have to wait a few days to get, say, a tail-light unit for it, or headlight- easily damaged stuff.

If that's not a put-off for you, then the Cypha is the better mechanical / electrical pick of the two.

The Will Cypha better have mechanical superiority on it's side. It sure won't win any prizes for style or beauty.
Strange how Jap or Asian designers in general repeatedly get monsters approved by the board. Front-end appeal of their cars isn't their strong point.