What are you planning to use it for and, frankly, how much do you care? I got the encore as it grinds consistently over a wide size range so it’s good for cafetiere and can grind down to espresso reasonably well. The Iberital above is a good espresso grinder but if you make lots of different styles of coffee it’s more annoying to adjust and isn’t very consistent at coarser grounds. The Aldi model is what it is, cheap and cheerful – better than nothing but it’s not going to do you an espresso grind and will be completely inconsistant size wise.
The Krups one is somewhere in the middle – reputation for lots of fines, fairly uneven grind, not really great for espresso but can just about manage – it’s a pretty good first choice but it’s possiblya step down from your Gaggia depending which model that was.