try OBS ((its free))

shadowplay is good if u have a nvidia gpu

OBS is great if you get the right settings done (doesn't take much time)
shadowplay if nvidia
camtasia if you want to go that route, good for recording and pretty user friendly IMO

I have both OBS and shadowplay, any reason to use one over the other?

obs is better but more confusing, shadowplay is simpler but less options and quality, although the quality of shadowplay is good for gameplay

OBS has better options ranging from quality to certain audio settings. Confusing, and what infinity said is exactly what they are.
I'd say use OBS for more local recordings (such as demos), but shadowplay for more "clip" video types. OBS can be used to do clips, however you'd need to record the entire time, where shadowplay can do some highlights, I forgot what they were called.

you can setup replay buffer in obs which functions the same as shadowplay (use for clipping stuff)
nvenc encoding in obs uses hardware acceleration just like shadowplay.

but if were talking absolute minimum input lag/frame loss, its going to be nvidia share aka shadowplay, you can use nvfbc which yields better performance than nvenc is able to

if you're recording demos for clips/movies i'd use OBS
if you're recording live gameplay for POV purposes i'd use shadowplay because of better performance

If you're recording demos you shouldn't use OBS, you should use Lawena to ensure perfect frame pacing and no re-encode troubles.

For TF2 anyways. OBS is fine for games that lack render outputs like this.

if you dont want to spend an hour rendering and dont care about having the best quality its fine to use OBS or shadowplay to record demos

is there any program that i can set to record for a certain amount of time then it stops itself?

for example if i wanted to record a full 30min demo i could set it to record for 30mins then just leave it?

you can do that in OBS