Which of these measurements is a good indicator of VHF receiver performance in an environment of strong out-of-band signals?

In VHF operation, strong out-of-band signals (such as commercial FM broadcasters or paging transmitters) are often spaced relatively far away from the desired amateur band frequencies. Measuring the dynamic range using a wide frequency spacing, such as 10 MHz, gives the most realistic indication of how well the receiver's front-end filtering and mixer will handle these common real-world VHF interferers. While the Third-Order Intercept Point (TOIP) and Blocking Dynamic Range are important performance metrics, specifying the Two-tone Third-Order IMD Dynamic Range with a wide spacing specifically assesses the receiver's ability to reject strong, widely separated out-of-band signals. Narrower spacings (like 20 kHz) are much more relevant for HF operation.