There’s a few threads on DA’s on here.
Look at DAS-6 Pro. It’s ideal for newcomers to dual action machine polishing. It has an 8mm throw which is the distance the plate oscillates, (some are 15 or 21mm) and is a versatile machine as it can take both larger sizebacking plates for 5 and 6”pads but also smaller 75mm plates for using 3” spot pads, which are usual for tighter areas and contours, B pillars, wing mirrors etc.
There’s the new DAS-6 V2 which takes 5 and 6” plate/pads but doesn’t take spot pads so some limitations. Same with the DAS-6 PRO PLUS which again takes only 5 and 6” pads but has a larger throw at 15mm. The larger throw means more coverage, which means quicker results with less effort in less time, but it comes at the cost of limited backing plate fitting.
I have the latter and it’s great but I also have Rupes Mini Bigfoot for use with spot pads, so got most areas covered. I started out with a Meguiars DA with 8mm throw and then upgraded when I wanted a bigger throw machine, and sold on my original.
So think about a machine that suits your needs now, in the knowledge you can sell it down the line if you ever want to progress or upgrade to something else.
Choose your DA first and then have a look at the kits available.
Good places to start.
https://www.cleanyourcar.co.uk/paint-correction/polishing-machines/dual-action-polishershttp://www.theultimatefinish.co.uk/machine-polishing/dual-action-da-machine-polishers.aspx