For reference:

16th: legalizes federal taxation that's not a fixed amount per capita
22nd: limits presidents to two terms
23rd: permits DC to choose electors for president

The 16th allows us to have any sort of proportional income tax, including the range from a flat (percentage) tax to a graduated one. While I would be interested in arguing about the merits of graduating the tax, I think it's quite clear that flat (per head) taxes are a bad idea. Tax everyone $5000 and you have a huge burden on the poor but a tiny one on the rich.

On the 22nd, yes, we should repeal it. If people want to reelect a president for a third term, they should be permitted to.

As for the 23rd, the right thing to do is either make DC part of another state or it's own state. The 23rd amendment is a bad compromise, but repealing it would not improve anything on its own.