I thought that the two sites mentioned in the OP rang a bell. I looked at them (briefly) when someone opened a thread on Beginners & Help suggesting some alternative crypto forums (which turned out as expected rather inferior in activity and content, although some sections seemed interesting like the video section in cryptocurrencytalk.com or the guides in mastersofcrypto.com).
I really cant be bothered with other Crypto Forums unless a pretty good reason crops up to ponder them over Bitcointalk. Even so, Ive taken a quick glimpse at the list (so my first impressions may be wrong):
Bitalk.org -> Seems to be Russian only.
Bitcoin.com -> Not too active (not bad UI).
litecointalk.io -> Not really interested in a Litecoin specific forum + rather inactive.
cryptocurrencytalk.com -> Rather innactive on substantial threads (I like the video section).
bitcoingarden.org/forum/ -> Very similar UI (SMF). Structure a bit weird, and 24K members only.
bitcoinforum.com -> Also very similar UI (SMF). Not very active, and just under 18K members only.
allcryptotalk.com -> Not many boards not activity.
cryptorum.com/forums/ -> Very weak in terms of boards and content.
talk.peercoin.net -> Specific to peercoin
mastersofcrypto.com/forum/ -> I like the guides .. but nothing else (+ barely any activity).
So, in summary, none of the above come even close to Bitcointalk neither in terms of content nor, very likely, prestige and history of its members.