I have two sets of the tubular three legged kind that I use and feel safe using-namely because they were made in the USA with solid steel. Not the thin stuff they use today. I have also seen where the (and I don't know who made them or anything behind the picture I saw) where the newer ratcheting style have sheered and collapsed. Leaving my floor jack under the car is a good idea as it ratchets up and down so there is a mechanical lock on the lift.
Don't go cheap on jacks!!! I have expiries with jack failure. Check the quality, how the pad is secured to the shaft, construction and supports. I Had set of jacks that failed up hill. In my youth, I always tried to have one hand on the car. Clem