Depends on what you mean by "backup service" and what you need. Are you looking to real time, or at set intervals back up your PC and keep that updated and in sync. Or do you mean you need to store/archive data onto a cloud backup solution and not often sync or update it.
For the first use case, I have been using BackBlaze for many years. Its fully unlimited per pc, with stipulations (no support for network drives and removable drives must be connected.) However, all my main data is stored on a re-purposed normal PC running Win11 as my NAS and media server. So can run BackBlaze on that and it real time backs up all my data. Also use it on my folks home bossiness computers. Have had to download accidently locally deleted files a few times. I at one point, uploaded 18TB worth of data to BackBlaze.
For data archive, i just use spare hdds/ssds. Do not use Cloud backup for long term data archival.
Though, i do use pCloud for photo and vid sync from my phone to cloud so that i can have it sync to my NAS the actual files. Also use Google Drive Workspace provided to me by a contact to store large amounts of data for some video related projects.