I'm currently selling a 16-unit apartment complex.

Four properties provide diversification, greater potential for appreciation, higher aggregate depreciation deductions, and increased cash flow over time but involve more management complexity and higher leverage risk.

I.e. a 5 unit apartment complex will likely only require an appraisal.  

Look around your town and find some relatively new apartment or condo complexes- who built them? 

With 2 rentals, i would keep it as simple as i could and one bank account is less complex than 2.  

What if you have an apartment complex with 20 units?

Please note I haven't used either but my understanding is TenantCloud has more complex accounting features. 

Pros include securing the desired property and strategic planning, while cons involve higher costs, financing challenges, and complexity.

The complexity of selling nationally forced us to expand our headcount.

I have personally purchased large apartment complexes from REITs and know how poorly some of them manage their properties.