I've been working on a list of strategies that I've seen here. This looks like a good time to print them out. In addition to your 4, I have:
5) Modify the traditional SWR (your 1) by reducing spending in years when asset prices are low.
6) Modify the traditional SWR (your 1) by holding both short term and long portfolios. Maintain spending when asset prices are low, without selling anything in the long portfolio, by withdrawing only from the short portfolio.
7) Modify the percent of current portfolio (your 2) by holding a short term portfolio for smoothing. e.g. the short portfolio starts with 3 year's spending. Each year, sell 4% of the long portfolio and put that in the short portfolio. Then, withdraw 1/3 of the short portfolio for spending.
8) Increasing percent of current portfolio. e.g. withdrawal amount is (current balance) X (1/life expectancy) or maybe (1/years-to-95).
9) Withdraw only interest and dividends
10) Withdraw only net interest and dividends ("net" means leaving some to accumulate to offset inflation)
11) Time buckets. e.g. One bucket has 7 years of spending in short term assets, the second has 7 years in intermediate assets, the third has the remainder in long assets. Completely exhaust the first bucket in the first 7 years. Then rebalance, moving bucket 2 to short term, and some of bucket 3 to intermediate. Repeat.
12) Horizontal buckets. Build a base of solid income, than add a higher risk/reward layer. e.g. the base is SS plus an SPIA to cover basic spending. The rest is in equities with an aggressive withdrawal rule like 7% of current balance
13) Notional lockboxes. Put the first year's spending in something very safe (CD's), the second year's in something almost as safe, ... getting more aggressive with each lockbox until you're 100% equities for the last year's spending. (I've only seen this in some academic stuff posted here, though I think some of us can see how to interpret our investment strategies in these terms.)
13) No explicit plan. Withdraw as needed, review annually, rely on a lifetime of LBYM to make good spending decisions.
14) Different types of floors on the percentage withdrawal (other than your 3). For example, 6% of current balance, with a floor of 3% of the initial balance (inflation adjusted).