I think IDEX should be better and even though this token is still not very strong or lacking in market interest, I think IDEX will last for a long time so investing there is still in the safe category, I guess. But all options depend on each individual, because I think there will definitely be different views about IDEX but I believe they can compete in the market time to time.
In my opinion, after this defi trend, DEX will not be as strong as you say. I feel the DEX still lacks a lot to compare with CEX. Besides, the volume at Cex still accounts for over 95% with normal days in the crypto market, the defi trend is only temporary and I still dont believe in DEX will have a new look in the future.
DEXs are good for occasional trades. Otherwise, the gas price will eat you up.
I found DEXs and DeFi for very useful as a concept, but I don't think that they will even come close to CEX in a matter of volume and usability.