I prefer 7zip, mainly because it's a lot faster and has a better progress bar, as indicated above. I really don't care how the GUI looks, since I'm not one of those who are obsessed with the appearance -- as long as it works, and it works perfectly fine. 7zip is smaller and faster even though it does not support as many formats (although I don't need such diverse support anyway). BTW IzArc is written in Delphi (executable is packed down to 780K, but it's actually moar liek 2.8M), which is likely the reason for it's lower performance. 7zip looks like MFC (executable is only 293K, not packed). We can compare codec modules from each archiver for each format: 7zip: IzArc: 7z: 137K 505K RAR: 56.5K 160K CAB: 43.5K 57.5K I don't think I need to elaborate. ...BTW, I use LZH/LH7 for my own archiving purposes. The compression is much better than ZIP, quite similar to RAR (sometimes better than).