I almost bought a 106 GTi after I sold my Valver, but got a Williams instead.
Its hard if youre a private buyer and want to get a good look at a car youve never seen before, so I went to look at half a dozen or so. I was impressed with the 106, dont get me wrong, but a lot of the stuff Id found so good about the Valver was missing - and each of the ones I saw was a dog.
The 106 seemed to miss the Valvers high speed stability and it didnt actually seem as quick either, although the figures are about the same (I had a quick Valver though with head done etc). The 106 is a smaller car than the Mk1 Clio and I didnt get one well with the interior at all, especially the pedals.
The main problem for me was the condition of the cars I saw. Some of them were only 2 or 3 years old at the time but were already pretty tatty (just down to owner profile really). I think I was unlucky - one clearly idled badly, another had no V5 document (well chuffed I didnt get that one!), all had corrosion to the engine bay, another had a sticky rear brake calliper and so on.
At the time I was disappointed, but thought that Id begin to look for a Willy as it was only the rarity and difficulty of finding a good one that put me off. If it was going to be hard to find a nice 106, I figured I might as well put the effort into getting a Williams.
Doesnt mean the 106 is a bad car by any means, but for me it just wasnt meant to be!
Do try a 16V or Williams - a 106 will seem great after an RT, but you need to decide between them not in isolation of each other.