I've got a diesel, do 60 miles a day to work and back and have no major complaints about economy - I'm getting just under 50mpg at the moment, and that's with a heavy right foot!
From what I can gather the mk1 (up to 2004) are built slightly better (but don't look as good IMO), I know a few mk2 guys who've had no problems so think it's down to the individual car... I think my mk2 (2005) was built on a Friday as it can be a little trying at times!
If you want really good performance then get a 180. If you want brilliant economy with good performance then get a diesel (115). Other than that the 110 (1.6)/120 (1.8) both do a 60 sprint in about the same time as the diesel yet aren't as punchy in gear, they return a good 10-20mpg less but on the plus side don't sound like a tractor!!