Its really hard to compare both on charts. Since both of them have different properties. The supercharger gets power down low and hits pretty smooth. While the turbocharger takes time to spool and is very unpredictable when it hits. Also the turbocharger improves your top end speed better.
A properly tuned and sized turbo system certainly won't be unpredictable.
The power delivery of each will be different, with more torque coming in lower on the supercharger, and more torque coming in at higher RPMS with the turbocharger. On dinky little engines like the Mazda 1.5, a turbo setup would probably net higher gains. A supercharger is belt driven and acually adds parisitic draw, like any other engine accessory (alternator, A/C compressor, etc.), as it adds power. Also, because of the Mazda2's sorta high compression ratio, I imagine a low-boost turbo set up would be quite drivable. 150 HP would make for a really fast 2.
Another thing to consider is if you're going for as much power as possible, a turbo is the way to go.
Potential benifits of a supercharger set-up would be easier installation, and probably less cost.
Anyways, I'm biased towards the turbocharger, and I think anything more than 150 HP in one of these cars would be overkill. Keep in mind, that's 50% more power, which is a huge difference and it would probably take a lot to get there. You only have 1.5L to work with, unless you're doing a bore/stroke or an engine swap.
Hope this contributes well!