Here's a list of reasons:

 • They have terrible security (80 million accounts were exposed early this year)

 • They have terrible customer service (just google it)

 • Games are more expensive on Epic due to regional pricing

 • You can't play games offline

 • Limited social features

 • No screenshots

 • No controller support

 • They broke EU laws

 • Scummy tactics (you had to tick a box to opt out of emails etc)

 • They are partially owned by Tencent (a company that sells user data to the Chinese government)

 • No achievements

 • No cloud saves

 • No game forums (many people went to steam for subnautica support)

 • Epic make you pay the transaction fee when purchasing games.

 • They are anti-consumer (They pay for exclusive rights to games to try and force you to use their store)

 • They can refuse refunds even if you meet the criteria

 • No reviews

 • No Linux support