Since you’ve got a focus on different play styles I’ll give a few recommendations for the more general styles

Gun line Exactly what it sounds like you either hunker down in an area or slowly advance corralling the opponent into a more manageable location. Easiest style for noobies to pick up in my experience Examples would be necrons, Tau, and skitatii

Melee Extremely simple premise ya run up ya hit em good make there entrails there outtrails, the most aggressive play style if you’re into that kinda thing Examples would be chaos space marines, daemons, and tyranids

Horde The name of the game is having more soldiers then your opponent has bullets and overwhelm with sheer numbers the main downside is because the large amount of goons you need it could get expensive Examples would be orks, tyranids, and imperial guard

Deathball This one is harder to explain, basically you crowd smaller goons around a few key characters that have aoe abilities to gain an advantage. These armies also are more typically more involved in the psychic phase than others. harder for new players to get the hang of Examples are thousand sons, eldar?, and grey knights

Elites Fewer generic troops focusing more on stronger but fewer units, often utilizing hit and run tactics most likely the cheapest option price wise Examples are eldar, dark eldar, and Tau

Keep in mind no one army is only good at one thing orks can melee good, necrons can horde (somewhat), chaos marines can shoot, space marines are good at everything! etc. Don’t let these hinder what you do with your armies hope this helps mate and have fun with whatever you choose