I have found that Google Dialer, combined with DND, is most effective at blocking spam calls. However, be aware that it may also block service calls at times. Truecaller Premium, even with all the blocking options like block top spammers, extended block list, etc., performs slightly worse than Google Dialer. Hiya (the one used in Samsung) is okay!
The only reason I use Truecaller is that I also want to make use of Samsung auto call record without any announcement to the other party. This is not possible with Google Dialer.