The best advice I could give is stay away from products that say they do 2 or 3 things as they are Generally all Poooo.
Polish is only a paint cleanser and thats all it should be used for, most of the ones mentioned are all good hand polish products personally I use Chemical Guys Pro Polish really good stuff and even better when machined rather than hand polished
If you want to keep the new shiney look then invest in some good sealant or wax, personally I use Chemical Guys JETSEAL 109 truely amazing stuff although at £22 a bottle it ain't cheap but I'll swear it's the best sealant there is. Paste wax is a good idea, there are many out there and in general the price reflects how long the Wax finish will last. I user Chemical guys 50/50 paste wax and the finish is fantastic and lasts a long time.
Generally I'll give the Fiesta a coat of Jetseal and wax every 5 months and regardless how dirty the car is after a wash it's always super shiney. Washing the car is so much easier too as nothing sticks to the paintwork due to the sealant and wax so tar spots and dirt fall off the car. It's been easily 6 months since the Fiesta was last detailed and it was still gleaming in the car park at last nights Meet with rain water beading all over it