The best is what brings you money and joy.
FBA is great but the entry barrier is higher as you have to invest in real stocks yourself and if it doesn't sell it's your loss. Competition between listing can be high. Be prepared to spend an initial investment of 2 to 3K to start with.
You don't sell the same kind of things also.
The best thing is you don't have to handle inventory and shipping yourself. You can sell with one day delivery. But margins are lower, you earn by selling high volume.
Shopify is ok if you have the money to pay for everything and the recurring monthly fees. Great for already rich lazy people or complete newbies. Or genius marketers that are able to sell crazy amount in less than a month... rarer these days due to high competiton.
Alidropship, the most advanced solution for wordpress to date. One single license fee + yearly hosting fee and you are good to go. You have full control over your site and database contrary to shopify or amazon. But you have to handle all the technical aspect of your site yourself. Thanks for you Alidropship is very straightforward with all the necessary functionalities in one single plugins.
Please google all of these infos. Do what fits your needs, there are no correct answers to what is the best.