Train to Florence

Origin?....

It would help a lot to know where you would be taking this train from.

If from any major city in Italy, then either a Freccia (high speed ) train by Trenitalia, or a train by Italo will get you there fastest. If from a small town or village, then your only choice may be the Trenitalia Regionale trains.

Trenitalia-official train company
Fast trains and regional trains
https://www.trenitalia.com/en.html

ItaloTreno-private train company
Fast trains only on selected routes
https://www.italotreno.com/en

Both have easy to use apps
Both are reliable