I am around 6 feet and I mainly side discharge.. Sometimes bag but usually not.
The engine is a 20.5 HP Kawasaki and I have a 48" deck.. would love to go bigger but didn't have enough money at the time.
Walkbehinds cut better because of the slower groundspeed and they are more versatile since they have the outfront deck. This means it can go in an out of tighter areas and they really cut down trimming time. Ive been running it for going on 3 three years and it was really worth the buy.. Its also great on hills
I would get a walkbehind first. Then when you have enough money invest in a Zeroturn or stander for wide, large areas. I prefer a stander since its better on the back to be standing all day