Best to have a drive in one you like.
1.8 and 2.0tsi have timing chain; EA888.
1.0,1.2,1.4,1.5tsi and all tdi's are timing belts.
tdi's should be changed every 5 years. TSI's are a longer interval I believe. The 1.5tsi has just had its belt change interval extended - don't know if that applies to all the TSI EA211 family?
Belt or Chain wouldn't sway my decision - the chains are not infallible, more susceptible to poor/long servicing - so buy on condition & history and the model/engine which suits your needs.