If you want to go e4:
The Ruy Lopez is complicated, but it won't baby you. I recommend it for all levels; anyone between a FIDE rating of 100 and 9999. The scotch is also an acceptable choice i guess, but i recently learned that at the top level it's actually just a draw. The Ruy Lopez secures an initiative for white.
Against the Sicilian, either the open Sicilian or the c3/Alapin Sicilian is a great choice. c3 Sicilian leads to isolated queen's pawn positions, which are very good for understanding more about the game of chess. The c3 Sicilian doesn't require a massive amount of theory either.
Against the french, just play the Tarrasch I guess. The Tarrasch is the most solid line against the french at the top top top level (in which almost nobody plays the french at the supergrandmaster level because it's passive and doesn't 'play for a win').
Against the Caro-Kann, you can try 1. e4 c6 2. d4 d5 3. exd5 cxd5 Bd3 which is pretty easy to play if you do a little of homework, though it might be kind of dry. The absolute best response against the Caro-Kann is the advanced variation where you play e5, but it's actually hard to play and hard to get used to because black gets easy moves, and the pawn on e5 and d4 feels kind of over extended and loose. And playing c3 to hold the pawn chain together is never a good move in the main lines.
Against the Pirc, 150-attack or Classical system are good. Look them up if you ever face the Pirc at your level. It's rare. You can also try f4 (Austrian Attack), g3, and Bc4, though I don't actually recommend the austrian attack. It's about dead equal but not very drawish at the same time.
Against the Scandinavian, just the main lines. The Scandinavian is also rare. Qd6 and Qa5 are two different systems and completely different.
If you want to go d4:
You can try the London system or just the main lines (d4 c4 Nc3 e4 setup). The London system is about equal (white wants to be slightly above equal), but it's super impervious, solid, and you'll broaden your understanding about chess, and there are a several grandmasters who play the London system.
London System = d4 Bf4 e3 Nf3 c3 Nbd2 h3 setup.
Whether you play the London system or the mainline d4 with c4, you are going to have to watch out for:
The Grunfeld. The Grunfeld is actually the best best best absolute best opening against the d4 if you go for the Nc3 mainline (1. d4 Nf6 2. c4 g6 3. Nc3 d5). The Grunfeld is very sharp and a lot of grandmasters are facing a little trouble against the Grunfeld. But, hey, grandmasters play d4 c4 setup, so it must be promising. The Grunfeld's endgames are always superior to white's in the main lines because of the 2-to-1 pawn majority on the queenside.
The Nimzo-Indian defense is also very solid and good for black, just right behind the Grunfeld by a millionth of an inch.
The Slav is right behind the Nimzo-Indian defense in soundness. The Slav can both be sharp and solid. Also the semi-Slav Botvinnik is the sharpest opening in all of chess openings. The Najdorf and the Grunfeld are just a little behind in sharpness but still super sharp.
I recommend one of the following:
-You can look at the English (c4)
-You can look at the Catalan
-You can look at the Reti, but you really have to like it to be good with it.
-Generally you want tactical and sharp openings if you're a beginner, because playing out their middle games will improve your tactics. e4 is sharper and more tactical than d4.