If all conditions really means ALL conditions then only the tricross will have clearence for spikes snow and ice tyres, also, it will take proper mudguards like SKS chromoplastics, blumells, or tortecs. Also, if you want do do anything unsurfaced or worse with any regularity then it has to be a tricross.
However, if you plan on only using the roads and when its gets snowy and icey you can use an alternative I would go for the allez. If will take crud road racers (but you may have to change the tyres to 23mm ones to get them rub free) and like the tricross it will take a rack. Much nice to get the weight off your back and have a tail pack.
I have a tricross and a Secteur (the secteur being similar to the allez, but not such a racy riding position). The tricross is a great do everything bike, but if you are sticking to the roads then a dedicated road bike will be better.
Its your call on what you want from your bike.