Get the best phone for you that works now. I know lots of people in this thread like to keep their phones for 10 years, but sometimes with technology you just have to accept that upgrades are necessary.
Get the best phone now, and if it has 5G or not, don’t worry about it. 4G is going to be around for a long time, and when the move to 5G requires a new phone, the 5G radios will be cheaper and more efficient than what is available today. Particularly if you’re looking at extreme budget phones. The extra cost to go from a basic 4G phone today to a 5G phone today is probably better spent buying a 5G phone tomorrow.
If you’re looking at more expensive phones that happen to have 5G, that’s fine, too, but it certainly shouldn’t be the deciding factor unless the other features and price are equal.
Also, the big feature of 5G (to the end user) is increased data speed. If you’re getting a phone that can’t fully utilized 5G speed because of its slow processor or because it’s not a smart phone, then 5G isn’t going to matter (until 4G goes away many years from now).