While I sympathise with your sentiments about iTunes – it’s easily the worst product ever to come out of Cupertino – if you use it as Phil recommends (compact in the How To Digital DJ Fast course, more elaborate in the Masterclass) and use a separate collection ONLY for your DJ-ing needs, it actually is, imho, the best thing for the job out there.
Second is managing your collection in DJ software itself, more limited depending on your DJ software but can be done.
For those outside of Traktor RekordBox is a viable if Pioneer-centered alternative or (with a few more updates) the new Denon Engine (clearly Denon-centered).
Outside of these likely suspects there isn’t much available. Things like MediaMonkey get mentioned here from time to time but are the exceptions rather than the rule.
Depending on what made you lose faith in iTunes, it might be fixable by adapting your workflow.
So, do share your worries with us, perhaps a few simple changes can prevent you from having to do over a lot of work.
As for transferring from iTunes, it’s depending on what info you want to transfer.
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