The practical size of a modern multipurpose frigate

What is the ideal size for a modern multipurpose frigate?

Arrowhead 140 is near the practical lower bound, with Type 26 and Constellation defining the upper part of the modern frigate bracket.

Arrowhead 140 is the suggested minimum size for a modern multipurpose frigate. Larger examples in the same bracket include Type 26 and Constellation. The comparison treats the modern frigate as an anti-submarine cruiser, which helps explain the size of these ships. Offshore patrol vessels are excluded from the question.