hey!
in my opinion, A levels seem easier than IB, not necessarily in terms of content, but in terms of workload - in A levels you usually do 3 (or 4) subjects, while in IB you have to do 6 subjects and TOK and CAS, you also have to do IAs (research papers or oral exams in languages) in all your subjects and EE in a chosen one. considering all of this, you should think if you want to spend so much time doing school work, it's not only about revising, my summer has just started and I feel like I'm gonna work on IAs, EE and TOK for all summer (and uni app on top of that, but everyone does that). on the other hand, IB gives you the chance to have a wider variety of subjects which is what I personally enjoy, but probably some people don't, like if you are very into science/maths, you might not like the idea of having (usually) 2 essay-based subjects.
I don't think unis have any specific preference, they even recognize some less-known qualifications, so whichever you choose, it'll be fine for the uni and if you're planning to apply to Cambridge, what's more important are the subjects and results, I know someone who got into Cambridge and is not from the UK and has done her national qualifications and still got in, what she needed was great results, not IB or A levels specifically. I would personally say that it is really hard to get like 42/45 (which is usually required by Cambridge), but it's not impossible, but it probably requires more hard work than getting e.g. 3 A* and A in A levels.
bear in mind, I'm not from the UK so I could either choose IB or my national qualification and decided to do IB, I can't say if I would change it for A levels (if I had a chance) because there are many cons and pros to both.
when it comes to Cambridge specifically, I think it would be good if you had Maths + 2 Science subjects at HL because some colleges require this and for others, it will be much more competitive.
btw, my subjects are HL: Chemistry, Biology, English B, SL: Maths AA, Polish A, Geography, so feel free to ask about any of the subjects (probably only Chemistry or Maths would be of your interest, tho
)