Which platform do we think is more reputable and have good track record of security?
DEX has it in this category as they can't often be the target of hackers because they do not have the central storage point to keep people's assets unlike CEX. This makes it less attractive to hackers unless they have another reason(s) to perpatrate their evil.
Does either of them have good liquidity?
Both are trying to build their liquidity but CEX has it here, the in CEX's liquidity is far more, it can't be compared to that of DEX. The reason is the businesses and convenience that CEX builds around its networks which attract more participants. Also, the users of DEX relies solely on the liquidity provided by the users, but CEX could create additional liquidity through strong external financial sources for profits.