My understanding is that executives prefer buybacks because they mostly are compensated with stock options, which don't pay dividends (until exercised) but which appreciate disproportionately from buybacks.

Dividends actually directly lower the stock price. Keep an eye on your portfolio when your holdings go ex-div -- the price falls because it no longer includes that cashflow.

It does not lower it in any long-term sense, because, unless it's a one-time dividend, there's another dividend next quarter, and generally assumed to be continuing payments for the foreseeable future if the company is healthy.

This doesn't sound correct. Giving out an expected dividend lowers a stock price since otherwise one could arbitrage it, but this is evidence that the dividend raised the price when it got priced in

Also, I believe in the US ordinary dividends are taxed at the income tax rate which is much higher than the capital gains rate.

No, most dividends are "qualified" and taxed at the long term capital gains rate, assuming you've held the underlying for a decent amount of time.

Still, they're taxed, whereas buybacks allow the shareholders to control exactly when they take income.

Also buybacks will tend to select for frequently traded shares with high cost basis, further reducing total taxes and selecting for longer term shareholders. They really are just better than dividends in every way.

It doesn’t make sense to compare ordinary dividends to capital gains - either compare ordinary to short term gains or qualified to long term gains.

Why? These are just rules in a made-up game. They can be anything we want.

with everything at record highs we'll see if we continue to prefer inflated share price over reinvestment in the business or increased dividends.