It really depends on your goals, risk tolerance, and management capacity.

One expensive property:

Pros: Long-term capital appreciation is possible if the property is in an elite area; the single property concept can be easier to handle; high-end tenants are a possible draw.

Cons: Market decline may bring financial risk that is very high; no diversification as all assets are invested in one property; difficulty in diversification if the property is performing poorly.

Multiple cheaper properties:

Pros: Diversification across suburbs and types; can reduce risk if one property underperforms; spreads income sources.
Cons: More management work; each property may have smaller growth potential; may include properties in less-desirable areas.
Another possible lens is not price but how closely the property’s characteristics match your investment style and needs. A more affordable property situated at an area with high potential for development and also a low-risk environment can potentially be more profitable than an expensive one in a stagnant market area. Also, if location, rental demand, risk factors really stack up, having just one high-end property can still be a smart decision.