I've redone a basement before that was destroyed by a sharkbite fitting that popped and flooded the basement. I don't trust them as permanent solutions. That being said, if your cut is square, you deburr and you mark with a depth gauge to ensure they are fully seated, they are rated for enclosed use. I suspect failures are related to skipping steps on the install and just shoving them on and hoping for the best.Where in the lines did you put the Sharkbites? I need to install a water softener and haven't used a torch in decades and don't want to mess it up but chickening out for using Sharbites to connect to rest of house if they spring a leak.
To install a frost-free faucet, i needed to tie into pex so I bought crimping stuff. I still prefer copper for many reasons. If you use expansion pex instead of compression ring pex (b vs a iirc), the fittings flow far better and I would probably prefer that to copper (but I'm not willing to invest that much in occasional use tools).