I once put slightly wider tyres (165 vs 155) on an old Toyota that didn't have power steering and it made the steering much heavier. Is there an option on your model of narrower tyres. Other than that I agree inflation pressure will have more impact that choice of tyre. Due to the increase in tread depth new tyres will lighten the steering in any case compared to worn ones.
On choice of modestly priced tyres I've used Nexen Eco Blue and they were very good. They may not be quite on par with expensive premium tyres but they always seem to come quite close in tyre comparison tests.