EZ and HD are probably the best mods to play if you're not at extra level diffs yet. EZ is a bit of a special case tho. You don't need it, but being able to play it may give you an advantage on certain kinds of maps (usually the more technical maps). The problem is that, despite it's name, it's hell and tbh, it's hardly worth it unless you're the kind of person that likes to set gimmicky scores.
HD is mostly to teach you to listen to the music and be patient with pressing your buttons, instead of trying to play whack a mole (which too many people do nowadays tbh).
You can play DT, since it doesn't really change anything about the map, just speeds it up, to become faster. I personally wouldn't wait too long with it (like i did, and now i still have trouble with most 200+ bpm), but i wouldn't focus on it too much either because that would cost you the ability to play slower maps.
You should stay away from HR until you can already consistently fc 5+ star maps and get good acc on them (only a few 100s, 99.5% acc or something). And you should play it for the accuracy, not for the AR. If you feel like you're starting to put HR on maps because otherwise the AR is too low you've taken the wrong road.
HD is mostly to teach you to listen to the music and be patient with pressing your buttons, instead of trying to play whack a mole (which too many people do nowadays tbh).
You can play DT, since it doesn't really change anything about the map, just speeds it up, to become faster. I personally wouldn't wait too long with it (like i did, and now i still have trouble with most 200+ bpm), but i wouldn't focus on it too much either because that would cost you the ability to play slower maps.
You should stay away from HR until you can already consistently fc 5+ star maps and get good acc on them (only a few 100s, 99.5% acc or something). And you should play it for the accuracy, not for the AR. If you feel like you're starting to put HR on maps because otherwise the AR is too low you've taken the wrong road.