Cable, ADSL, VDSL, ADSL2+ are ALL shared platforms, where the total number of users currently consuming bandwidth impact the available bandwidth for each individual.

This is how the Telcos bring the price of bandwidth down to 30-100 CHF per month

Fiber to the home (FTTH) is ALSO based on shared bandwidth in order to keep the costs down

COMPARE:

100 Mbps on a shared system = around 100 CHF per month

100 Mbps on fiber, with guaranteed bandwidth, = 10 to 50 times the price (1,000 to 5,000 CHF per month)

The factor 10 to 50 is exactly what the Telcos use to make the shared systems much cheaper: they take the guaranteed bandwidth and divide the costs amongst the anticipated amount of shared users - this is called over-selling or over-subscription, and is practised by every Telco around the world.

If you really want to find out which Telco and Technology performs the best for a home connection, you need to find out what over-subscription ratios the telcos use - and they all keep this info very very secret