-if you eye for long term...
-right now that you are currently having a problem on verification at the mentioned exchanges for weeks...
-you really need to buy bitcoin right now...
-you are fine with XAPO fees...
I don't see any problem if you used XAPO to buy bitcoins. All exchanges are good for buying, it's just that they have different fees. But since you are a verified XAPO user, you are now one click away for buying bitcoin at them so you can consider it now rather than waiting for long period of waiting for your verification on other exchanges on which some of them takes months.