I bought a Grainfather in January and went through exactly the same deliberations as you. One day I was going for a Brewzilla, next day Grainfather. Finally opted for a Grainfather and 13 brews in I have no regrets...... but I doubt I would have regretted the purchase of a Brewzilla either!
The comments that everyone has posted are pretty much spot on. No one is trying to mislead anyone. There are small differences between the two systems and a fairly sizeable £ difference. Ultimately you just have to decide if the differences are worth the extra £ for you.
Why did I choose the Grainfather?
- proven reputation/established/reliability/marginally better construction
- liked the counterflow chiller
- position of the controller
- the Wi-Fi connection was a bonus but not massive in my decision making
For me, the main shortcomings on the Grainfather are the lack of a false bottom or cam locks. Both of these can be retrofitted, albeit at more cost. Can't find a way to add a lifting handle though!
For me, the main advantages of the Grainfather are the controller position and the Wi-Fi and these can't be retrofitted to the Brewzilla.
When I made the purchase decision I thought the Wi-Fi was a bit of a gimmick, but to be honest I find it increasingly useful. Do your recipes/brew steps in comfort on Brewfather/Grainfather App and then with a press of a button it transfers over to the Grainfather controller. It does allow you to be more mobile on brew day but still keep an eye on what's going on. One nice feature occurred when a brief power shortage caused the Grainfather to switch off/reset midway through a mash . The controller on the IPAD saw this and asked if I wanted to go back to where the power interruption occurred. Pressed 'yes' and all the steps were reinstalled and I was back to the point where the power supply was interrupted. Loved the Wi-Fi that day! No idea if the Brewzilla has a similar feature.
The position of the Connect controller is for me, a big plus. I have built a mobile three level trolley for my system. Grainfather at the bottom near the floor, counterflow chiller in the middle, boiler for sparge water at the top. This allows me to easily connect the chiller to the Grainfather pipework, or lift the grain basket and sparge into the basket using gravity. The position of the Grainfather controller allows me to do this, otherwise I'd have be on my knees to access it. If I wasn't using a counterflow chiller then probably raising the height of the main 'brew unit' wouldn't be as much an obstacle.
In summary, you will brew great beer on both the Brewzilla and Grainfather and I'm sure no one can tell a difference in the beer produced between the two systems. Only you can decide if the way you want to brew suits a particular type of kit and no denying the price factor is a big thing.