B.K.
I used the baby Bjorn potty chair. My husband had a different potty he used for his daughter, but it didn't work for my boy because boys "splash", so getting a potty with a splash guard is good. Also I liked the baby bjorn (the bigger one) because it had a solid bottom and didn't tip. Easy to clean as well.
My son was a late start at 3 yrs. Good luck.