Question about buying SPY call LEAPs

Have been getting burned too many times buying short term (4 or 6 month) single company call spreads. Looking to switch to SPY call spreads. For those of you doing this, what spread width and duration do you find most successful?

The appeal to me of SPY call LEAPs is much better gains compared with buying SPY shares, while still having enough time in the market in case of downturn (though there’s no guarantee of course that the market won’t be down for 1-2 consecutive years).

Looking at buying SPY $470 call/selling $520 call with 12/2023 expiry.

Thank you in advance.