Cheap with Fewer Compromises
Estimated Cost: 100-200€
This option allows for almost no compromises in quality compared to much more expensive cameras (until you get to about 1000€, you will not get much more quality). The more modern sensors with high resolution and excellent dynamic range will scan both slides and negative film very well. The more modern ergonomics and performance also speed up scanning and make the whole thing more pleasant. However, these cameras still do not have tethering - if this is an absolute requirement to you, you might want to look at DSLR options from Canon and Nikon in the same price range (though this will compromise quality of the final scan compared to the mentioned cameras), or you might want to upgrade to the next category.
These sensors are newer, providing both better resolution (16-24MP) but also less noise in darker areas (signal to noise areas) making them very suited for scanning slide film. If you have no need for tethering, this camera category is really the 'best' you will need to go for most uses.
These all have excellent articulating (moving) screens on the back with higher resolution, making for better and easier focusing and framing
Little shutter vibration
The shutters on these cameras either have fully electronic shutters (Fujifilm) or electronic front curtain shutters (Sony - almost as good as it minimises the amount of vibration present during exposure)
Excellent quality to price ratio
This is the category you should land at if you are looking for the best final image quality to price ratio. Going up from these cameras gets very expensive for not that much return.
None of these cameras will tether to a computer. This means you have to take out the memory card every time you want your scans onto your computer. Some of them do have WiFi tethering, but it is in our opinion not an adequate option. Mirrorless manufacturers have generally done this to up-sell their more expensive models, so it is mostly there that you find this feature, starting with the Fujifilm X-T2 and the Sony a6300.
Lower resolution: Fujifilm X-T10
The X-T10 has lower resolution than the other cameras in this category (which range from 20-24MP) but we have still mentioned it because it is the nicest camera for using as a photographic camera. If you want a camera very capable of scanning but also one that you can detach and bring out with you - this is the one. It provides a really nice experience as a photographic camera! The Fujifilm X-T20 provides the same experience but with a higher resolution 24MP sensor - at about double the cost.
In order of priority
Fujifilm X-A20 - Sony Nex-7 - Sony a5000 - Fujifilm X-T10
The Fujifilm X-A20 and Sony Nex-7 are similar and will make about the same scans. Which one you choose will be down to the availablity in your area and potential brand-loyality. The Sony a5000 is older and lower resolution but still excellent for scanning. See more on the Fujifilm X-T10 above.