What exercises are best for building strength in my legs?

I'm not bothered about size or looks just raw brutal strength gains lol to assist in trail running, i have some beasty ass hills to look forward in the coming months but i have always struggled with my skinny pins as i live in the fucking flattest place in the u.k.

I'm running more trails in training and doing hill work at the gym, also throwing in some balancing excercises.

I have been doing basic stuff at the gym lately and feel a massive difference, such as leg press, calf raises and quad/ham curls etc but to be honest, all the years I've trained I've never trained legs due to always running road and never really needing to, any tips will be welcomed

__________________
There's no such thing as bad weather, only inappropriate clothing. Sir Ranulph Fiennes

If you're going through hell, Keep going. Winston Churchill