I just don't use Epic myself but do use Gog and Steam (with the ultra shitty EA launcher and Ubisoft Connect bundled with some of my games) and Playnite has changed everything unifying it all into that single launcher.
Full screen mode in Playnite works fine on my HTPC and as a launcher it does consolidate all of them into one place easily. Worth trying if you use multiple stores.
As for why I'm not using Epic, the whole paying for exclusivity with third parties really didn't appeal to me at all.
If the free offerings from Epic do appeal to you, or if they do better deals on localised currencies (especially if you do struggle to pay for things), don't worry about using their services. I wouldn't want you to deny yourself some entertainment just because other people have issues with them as a business.