@evelyn It's not an easy one to answer as there are a lot of considerations and factors involved.
The shortest answer, if you are using Windows, get a dedicated software for each purpose:
* anti-virus
* anti-malware
* anti-spyware
At least those three. Relying on a software that can do more than one, is not a good idea because the extra feature is not their focus nor strength.
An anti-virus software that can also detect malware and/or spyware can only detect so much in the malware and spyware categories; their main focus is being an anti-virus. Thus, getting a dedicated anti-malware and anti-spyware is highly advisable.
You should also not rely on one software per purpose/category. Get at least two anti-virus software as they can detect what the other cannot.
That is, if you are using Windows. If you are using Mac, let's say that less 50% worry. If you are using Linux, your worry level is close to 0%.