Recently, there has been a strong movement to "one-bottle" systems. These all-in-one solutions are the easiest and quickest to use. However, if you are particularly sensitive to chemicals, it may be better to use a hydrogen peroxide system.
In most countries, lens care systems go through rigorous testing to meet government regulations to ensure that they are safe and effective. Your eye care practitioner will recommend the care system most appropriate for you. You should not make your own lens care solutions, nor should you mix different brands of solutions unless instructed by your eye care practitioner.