Gyms are better against spoofers. If your pokemon stay on a gym for 8HOURS and 20min, you get 50 coins max a day, you also benefit from going to the same gyms and beatings rival gyms, beat each 3x and you can claim the gym, no more 10 lvl blisseys, 1pkmn of each species. 6 max.
You benefit in taking and holding gyms because of the same team bonus and as you lvl up your gym you get better chance of items like max rev. Max potions, and 10km eggs. I have not seen a 10km egg in a while, brought 8 incubators to clear slots, no 10km eggs until a random one showed up. Was stoked because I was close to maxing my 98%iv dragonite with an uncommon dratini. But got a dam mantine. Second spin on a same team gym and I got a 10km egg
Raids are cool, I would participate more but I don't see gyms from my house, do note that as a raid boss egg appears it takes 2 hours for it to hatch. But you have an hour to beat, I am lvl 32 and I'm sure I can take some lvl e Raids solo, but lvl 4 have 25k cp, so unless they have 4x weakness, it would be harder to take down. The raid meta is dif from gym meta, where as resistance is a major factor on surviving, they introduced immunities. You still take damage but it's laughable.
A good way to enjoy Raids is to visit an area with a lot of gyms. You get a free pass everyday. If you want to participate in more you would have to buy em. Note that pokemon you beat in Raids are catchable exclusively through premier balls, you get them after the Battle and depend on the damage your team did and the color the gym was. Like eggs, these pokemon have a higher chance of having good ivs. After you defeat the pokemon you get special items like rare candies (any pokemon s candy), tms (a reroll on moves), golden razz berries (any greater chance to catch).
Notable pokemon from lvl 3 are machamp, alakazam, eeveelutions fire water elec,
Notable pokemon from lvl 4 are tyranitar, starters, Lapras, Snorlax. So for 100 you get good items and pokemon, if you can catch em.