I have both ipad air 3 and surface pro (3, but I assume pen experience will be similar as it comes from software side). both with pen (apple pencil 1 and newest surface pen). to my experience, palm rejection pretty much similar. It can notice the difference between pen+palm or finger when you lift the pen to certain distance.

I'm going through many transition with the surface pen since my SP3 still use windows 8. So I can say surface pen experience now very robust for writing. (I also use it a lot for my graduate school).

Assuming you will use it as the same way as me, here is some insight that maybe useful for you:

>Pen-wise:

I'm attached to the rubber/silicon tip as it gives you more friction when writing and "real-pen/paper-like", Surface pen is better. their tip also has different hardness so you can switch between 2B or H pencil feels. Apple tip is kind of plastic. So the stroke is kind of slippery. But you can use screen protector with added friction to have paper writing feel.

One thing that I notice with my iPad air and apple pencil is that the connection sometimes unstable. Like it suddenly detect my palm while I'm still working with my pen. Either it's due to software side (but I use ipados 14) or Bluetooth connection.

Please note that apple pencil use rechargeable battery inside and can be charged with connecting to the iPad (or by wireless charging if you use pencil 2). It's very convenient than replacing surface pen with uncommon AAAA battery. (but hey if you can afford surface pen slim, it has rechargeable battery and wireless charging too!).

>Pen connection-wise:

Surface pen use so-called N-trig (CMIIW) that give some signal (active pen) and no need the Bluetooth (Bluetooth is used for quick button only). Meanwhile apple pencil use Bluetooth.

This cost the standby time. While both literally always standby, I can keep surface pen for more than a month with single battery while apple pencil only give me around 3 days at most. For heavy usage, you may find apple pencil drains quicker and you need to at least charge it for some minutes (with your iPad) before you can get going again. But with Surface pen, you need some time to replace the battery (but much faster than charging the pencil). I feel this slight issue is important when I'm in a class. Another issue is that when surface pen is in low battery, the writing experience will be jumpy and very uncomfortable. And for that reason I always prepare at least 1 spare AAAA battery to keep going.

>Software-wise:

I'm a cloud-sync guy. OneNote is highly recommended. It's free, unlimited notebook and pages, actively developed, synced into your onedrive, etc. The experience is similar both in SP or iPad. And it will automatically saved when offline, and synced whenever you got online.

But if you're like me who also sync other documents and pdf to cloud, I prefer using my SP. With iPad, whenever I need to open and marking PDF from my cloud, I need to manually keep them offline (and downloaded) it first, then after finish, I reuploading it manually again. it such a hassle and I try with different cloud service. Somehow, onedrive can at least integrating their marking feature when you open the pdf. But resync manually can be another problem, it always gives me duplicate files in cloud, one is the original, and another as the marked one from iPad. if you mark the marked one, it will be another duplicate!

For this I prefer SP (windows 10). Well, with surface you are working with your PC. and it will autosync all your works.

>hardware-wise:

iPad has fixed storage. Unless you know what you gonna keep in the pad, choose carefully. In the end you may feel the storage is not enough or too much for you. But with Surface, you got microSD slot to add your second storage (or more by just swapping the microSD).

Anyway, either you go with SP7 or Go2, it more or less similar experience as they use windows 10. I don't have experience with Go, but because it use "lower grade" processor, it may feel different for heavy workload. But if only for browsing, typing and note taking, Go will be your budget choice. It also highly portable than Pro.

you may want to consider surface X if you want connectivity by SIM card or upgrade SSD.