Ford Mondeo or Citroen C5 – Gasoline Searched

Hello together I am actually looking for an Opel Omega B2, with the 3.0 or better of the 3.2 machine. I unfortunately missed an unbeatable offer, or could not buy a very well-kept Omega for many reasons at a reasonable price. Unfortunately it is very difficult here in Switzerland to find a well-kept Omega, yes almost impossible, and I have been looking since September. Now I have looked around for a few alternatives and following two Exempla re discovered: Citroen C5 3.0 V6 Combi as automatic / 2002 year of manufacture, 135,000 km, private, 20.01.2011 MFK (TÜV). price 2400.- CHF Ford Mondeo 2.5 V6 Combi, switch / 10.2001 year of manufacture, 129,000 km, made at 128,000 km service, with leather Navi, Xenon etc. MFK 16.11.2011, so still by the end of this year Gutha habe. price however 3500.- CHF My budget is quite limited in terms of purchase, the price of the Citroen tells me more. Which is the more reliable and better suitable for purchase? What are the strengths and weaknesses? Is the 2.5 liter machine at the Mondeo as vulnerable as the ST220 up to the facelift, which is constantly bad with engine damage? Do you have a link to a large travel limousine? The primary reason for this is that I can drive 2000 km in the summer, therefore only a 6 cylinder from 170 hp is possible, besides only petrol, no diesel! I hope for many cars. pps. Thanks and greetings