Which is the best and cost effective way to swap coins ?

Guys , am a hardcore HODLER , so I been mining coins and HODLing them , so lately I came across a lot of coins and projects which am very much interested in , just that they arnt pow coins , but POS or so , so I can't really mine them

So I thought of swapping my Eth,BTC or Nano for them (all 3 I do mine ) , I tried some exchanges and also some swap sites , exchanges seem to have high fees to swap and swap sites have less fees , but still are there which are very high if you ask me , like for example I swapped 37 NANO for like 27.93 MANA , so that's a huge price difference , I mean thats 111.5 USD worth of NANO I swapped for 80 dollars worth of MANA , you see the huge difference right , there is like 31 dollars difference.

So guys what are the ways you swap coins for other coins or is there some other way you sell your coins and get other coins ?

Thanks in advance