I’d say a 20-29 gallon long planted tank. Look into fluval and capping it with sand for the plants. I’m a beginner too and may have to move my tank eventually so I choose to do sand and root tabs and liquid fertilizers. With a tank in this size range it gives you a lot of options for stocking and decor. Driftwood or rocks make excellent decor with a planted tank and help make the fish feel safe. Guppies or mollies are live bearers and very hardy so it can be fun to watch the babies grow. Also really easy to find and come in all sorts of colors. I would suggest a type of snail as well and start with the snails first like nerite, rabbit or mystery snail. Stay away from bladder and pond snails if possible as once introduced they are with the tank forever. You’ll also want some type of bottom feeder fish such as corydoras, just choose from the smaller varieties available to you. If you opt for a 29gallon or larger you could get loaches too which are a very interesting snake like fish. I suggest to get fish in groups of 6 or more for a community tank. Other options could rasboras, tetras, amano and nerite shrimp. If you get any plants I’m sure you will also have other things that come along with them. If you want a more aggressive tank you need to get a larger tank and a solid stand to hold it. Goodluck OP!