What are the benefits over something free like https://www.waveapps.com? I've had success with their invoice and accounting for many years.
I built this because people were asking me for it before I sold my previous software business. I know tools like WaveApps (and countless others!) are really useful but I think invoicing built into WordPress does meet a need.
I think they also have a paid support option but I can't remember, it's been a while since I used them.