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I've used Xapo at one point (2015-16) and BitGo, which until recently had the majority of my coins. I had no issues with BitGo, I was also provided with the private keys on sign-up. Furthermore, I never had any issues with the support or the wallet itself. It's one of the online ones I would totally recommend. It also supports Litecoin and Bitcoin Gold or Cash, don't remember which of the two.
I am yet to explore BitGo but i used Xapo and Coinbase in the past when there were literally no transaction charges and i used to enjoy sending coins for free but once they came out with variable fees i just stopped using them altogether but i do use Coinbase as it is convenient now to purchase the coins.
Xapo on the other hand, is lacking support. I haven't used it for years, but when I tried to recover my account, their support was unhelpful. It's been over 10 days and still haven't managed to recover it.
Xapo has the worst support team and it will take a long time to get any response from them and their mobile app is crap as well.