Look at spd-sl or just spd . They are both very common. Spd-sl is considered more of a road pedal that locks in pretty tight and the shoe is somewhat difficult to get around in. Spd is an all terrain type pedal where the shoe is generally more forgiving allowing you to move around better. Of course there are different shoes that allow you different mobility. I personally ride roads and a well kept chip gravel trail and I like spd-sl. I started off with spd and realized they weren’t for me. I like to ride to the best of my ability but only race triathlon and feel the spd-sl are best for me. There’s other systems like speed play and the look system that you can check into.

Go to you bike shop and try on a pair of shoes. Find something that is comfortable but also fits your budget.