What stretches are the best for being able to do the split and the side split? I'm already very close.(like 170°-165°)
You are at an advanced stage of stretching, given the numbers you provide. However, stretching does not increase your capability to stretch!
Think of your muscles like putty. When you roll it so that it gets longer and longer, what happens to the mass of putty? Yes: it thins out. This is not good for martial arts. As an example of what I'm saying, try to throw a kick as high as you can - but hold it for 5 seconds. If you can hold it for 5 seconds at exactly the same height the moment you threw it, then you have good strength. But if your foot drops a few inches, that means, you have the flexibility to reach that high, but you do not have the strength to control it. This is an extremely common problem that martial artists have: great flexibility, horrible control. I don't know your situation, so, I don't know if this describes you. If it does, read on. But if not, then keep doing what you're doing.
As you stretch, you need to add bulk to your muscles. This not only gives you the basis for control over your kicks, but it also reduces the chance for injury. PNF (or isometric) exercises are what is needed here. Such exercises typically require a partner, and you need to engage a wide variety of exercises to build up bulk in your adductors, abductors, glutes, and - very important - your lower back.
If you don't like PNF/isometrics, you can do dynamic stretches, but you'll need to implement weightlifting to get that bulk. Dynamic stretches can be done any time without warmup (they can be your warmup for many exercises).
From a martial arts perspective, it's important to have good control over your kicks. Without it, you can seriously injure yourself, or a partner or competitor - or both.