Welcome to the forum Donna
It all depends on your budget, but when buying a 9n I'd always recommend the options below as 'must haves'. Whichever model you choose...
1) Remote Locking
2) 15inch Melbourne alloy wheels or above
3) Metallic paint and/or colour pack
BTW, are you buying new or used? Since mid-2003 there have been various price and specification changes. If you need any help on this front let me know.
Next thing you have to decide is what engine you want. If you just want something that feels brisk and can hold its own on the motorway then i'd suggest the 1.2 65bhp model purely due to its flexability. If you want more performance then i'd suggest the 1.4 FSi which has almost the same performance as the 100bhp 16v but is capable of consuming an average of only 47.9 mpg on the EU combined cycle.
Although some people have had problems with there Polos (myself included) these can in all honesty be put down to early production niggles which affect every car. I have yet to see a supermini that can offer what my Polo can
