I feel I'm qualifed to pass comment on the merits of both cars since I ran a MKII 172 with Eibachs for 2 and a half years before my current car, a manual BMW 325 Sport (E46). Totally different cars requiring different driving styles. Performance wise they are virtually identical, 0-60 around 7 seconds, 0-100 a shade under 18 secs. Automatics, which most are, are around a second slower in both benchmarks. The BMW is in a completely different class in terms of build quality, ride and handling composure and overall engineering. Its more comfortable on A roads and motorways rather than windy back roads and B roads where the Clio definitely has the edge. BMW tend to be conservative with their power ratings, the 325 having 192BHP (not PS) and its not unheard of for some to have RR'd at around 200bhp mark. The 6 cyl 2.5 is creamy smooth and free reving and sounds great at high revs, the CLio reving even higher with an extra 1000rpm is more rawcous and hyper active in response.
It has to be said that the Clio is definitely more FUN to drive and a lot more nimble where as the BMW encourages a more relaxed driving attitude, though its not to say you can't be a hooligan when you want to in the BMW, especially with the DSC turned off on wet roundabouts. I've not experienced any negative attitudes from other drivers as a BMW driver either and have no problems with people letting me out of junctions for example.
For those who say all BMW are cr@p, drive one (Sport model if you can) and then pass comment. If you can get past your badge predjudices and take the car for what it is and not the stereotypical attitude of others, I believe your views will be a more possitive one.
I'm not a rep, its not a company car and I drive with consideration to other road users and love my 325 but I still hanker after an Clio and regularly check prices in Autotrader website for 2nd Clio 182s, despite their shortcomings, (build, driving prosition) I'm still addicted to the raw edge and fun of the Clio 172, but at the end of the day the family has to comes first!!