Orochimaru is a scientist not a medic and kabuto medic wise will never out do sakura or tsunade because Katsuya chain link healing is op.
Saying Tsunade is a better medic because she survived being cleaved in half is the same as saying kushina is a better jin and stronger nina than naruto because she lived getting kurama extraction or karin stronger than sasuke because even though both received fatal blows karin was still awake and probably would have lived even without medical help. These aren't feats, these are lineage perks.
Feat wise both have done amazing things. Tsunade of course would have more medical feats because she has been a medic for awhile. Even though Sakura hasn't been a medic as long as Tsunade she hasn't an excellent rapsheet. She has created a cure for sasori poison( one which sasori needed reference material in order to make), she kept naruto alive after he got kurama extracted, and sakura healed an entire army using Katsuya chain link healing. Putting what you know of Tsunade feat with Sakura, only illogical people who hate for sakura clouds their judgment would think that what one can do the other can't when it comes to straight up medical needs. The only thing sakura can't do that Tsunade can is restoring someone chakra without needing the full activation of the byakgou(butched spelling) seal (refer to obito and sakura trying to get sasuke back).
Also, Tsunade is comparable to the Sage of Six Paths when it comes to medical ninja. You don't surpass instead you embody their legacy. To that note the only person comparable to Tsunade would be Sakura.