It would seem logical that Qatar Silver would be oneworld sapphire, with all the benefits that come with it:
However… Although oneworld benefits are standardised, so that when travelling on another oneworld carrier you will get these benefits, you should note that your “home” airline may give you additional benefits. So, for instance, if you compare CX Marco Polo Club Gold benefits to the standard oneworld sapphire benefits, you will see that Marco Polo Club members get quite a lot of extras when flying on CX as opposed to another oneworld airline, including extra check-in and carry-on baggage allowances, guaranteed economy seats, free extra-legroom seats, and so forth.
You should also take a look at whether it is easier to achieve the requisite status with a particular carrier. I just did the maths for all the oneworld carriers, and with just 55,000 miles it is possible to get oneworld emerald status with Royal Jordanian (and to maintain it thereafter with just 50,000). Compare that to 80,000 miles to get CX Gold (oneworld sapphire) and 120,000 miles to get CX Diamond, and it is a bargain! Emerald status will get you extra free baggage on all oneworld airlines, plus first class check-in and lounge access, and more besides
At the end of the day, you need to work out which benefits are most important to you, and how you can most easily get them. For example, I am sticking with CX despite the higher qualification requirement (a) because I achieve it and (b) because of the extra benefits of having membershp with my home carrier (not least, being able to use CX lounges even when not flying oneworld, plus the ability to guest two people into the lounge rather than just one). My wife, however, is likely to switch to Royal Jordanian because although she qualified for CX Diamond this year, we know she won’t be able to renew it (she would only get Gold) so it is more sensible for her to get oneworld emerald status with RJ – that way she will get largely the same benefits as CX Gold PLUS first class lounge access
It is all horses for courses…