There are essentially four classic, moderately easy ascents up Mont Blanc: the Gouter Route, the Three Mont Blanc Route, the Grands Mulets Route and the Aiguilles Grises Route.
The Gouter route is generally considered to be the easiest ascent of Mont Blanc and, as such, is the most frequented. The tramway du Mont Blanc will take you from St Gervais to the Nid d’Aigle (2300m). From here there is a relatively easy climb to the Gouter hut (3700m), the only objective dangers coming from rock fall between the Tete Rousee and Gouter huts whilst crossing the Grande Couloir, and the Gouter hut will undoubtedly be crowded. The first part of the summit day is best tackled at night commencing between 1am and 4am; this means that you will arrive at the summit in the early morning and have plenty of time for the descent.
The Three Mont Blanc route is another popular choice of route which can be completed in a day. Starting at the Aiguille du Midi (3842m) this route skirts over the summits of Mont Blanc du Tacul and Mont Maudit before reaching Mont Blanc. The main objective dangers to be found on this route are on the north face of Mont Blanc du Tacul where there are some hidden crevasses and risk of both serac falls and avalanches. The section of the Tacul and Maudit are both quite steep with section of 35/40 degrees, and make this the most technical of the four routes.
The Grand Mulets route is the easiest ascent technically and was the route taken by Balmat and Paccard when they became the first people to summit Mont Blanc. This route can be a bit long and tedious especially as the summit day involves 1700m of ascent. There are also many crevasses on the approach to the Grands Mulets hut, and at the Grand Plateau and Petit Plateau one also runs the risk of avalanches and serac falls.
The Aiguilles Grises route is, perhaps, the most natural way to climb Mont Blanc as it uses no mechanical transport. However, the approach to the Gonella hut on a stone covered glacier is long and tiring, and the altitude gain on the summit day is 1700m. However, the route is never crowded and is a nicer variant than the Gouter or Grands Mulet routes.