StringBuilder v different String.Join overloads

SBvSJBenchmarks.cs

using BenchmarkDotNet.Attributes;
using BenchmarkDotNet.Columns;
using BenchmarkDotNet.Configs;
using BenchmarkDotNet.Jobs;
using BenchmarkDotNet.Reports;
using System;
using System.Collections.Generic;
using System.Text;

namespace Benchmarks
{
    [MemoryDiagnoser]
    [Config(typeof(Config))]
    [SimpleJob(RuntimeMoniker.Net90)]
    [HideColumns(Column.Job, Column.RatioSD, Column.AllocRatio)]
    [ReturnValueValidator(failOnError: true)]
    public class SBvSJBenchmarks
    {
        private class Config : ManualConfig
        {
            public Config()
            {
                SummaryStyle =
                    SummaryStyle.Default.WithRatioStyle(RatioStyle.Percentage);
            }
        }

        private string
            title = "Mr.", firstName = "David", middleName = "Patrick", lastName = "Callan";

        [Benchmark(Baseline = true)]
        public string StringBuilder()
        {
            var stringBuilder =
                new StringBuilder();

            return stringBuilder
                .Append(title).Append(' ')
                .Append(firstName).Append(' ')
                .Append(middleName).Append(' ')
                .Append(lastName).ToString();
        }

        [Benchmark]
        public string StringBuilderExact24()
        {
            var stringBuilder =
                new StringBuilder(24);

            return stringBuilder
                .Append(title).Append(' ')
                .Append(firstName).Append(' ')
                .Append(middleName).Append(' ')
                .Append(lastName).ToString();
        }

        [Benchmark]
        public string StringJoin()
        {
            return string.Join(" ", title, firstName, middleName, lastName);
        }

        [Benchmark]
        public string StringJoinArrayRange()
        {
            return string.Join(" ", new string[] { title, firstName, middleName, lastName }, 0, 4);
        }

        [Benchmark]
        public string StringJoinObjectArray()
        {
            return string.Join(" ", new object[] { title, firstName, middleName, lastName });
        }

        [Benchmark]
        public string StringJoinIEnumerable()
        {
            return string.Join(" ", new List<string> { title, firstName, middleName, lastName });
        }

        [Benchmark]
        public string StringJoinWithArray()
        {
            return string.Join(" ", new string[] { title, firstName, middleName, lastName });
        }

        [Benchmark]
        public string StringJoinWithSpan()
        {
            ReadOnlySpan<string> span = new string[] { title, firstName, middleName, lastName };
            return string.Join(" ", span.ToArray());
        }
    }
}

Output of a single run: