SSJG Goku vs Beerus

I got ssjg goku like 3 times so he is at 4-stars. What team is he good in?

You can use GodKu now (on saiyans team) but Beerus doesn't have team yet (he shares tag only with Godku). Once we get more "God Ki" units (SSB Gogeta maybe? SSJ Rose Goku Black?) they booth should be amazing.

I think Beerus is stronger than ssj god goku in terms of unit usefulness as beerus can destroy cards with his ultimate and that can potentially destroy special arts cards(blue cards) or even ultimate move(blue card gained from main ability), gain ki faster than almost any unit in the game usually after using all your cards to combo an opponent , debuff enemy ki restoration with your special move and every time he enters the battlefield, he locks all enemies’ main abilities and increases opponents blast arts cards by 5, essentially debuffing the overpowered sp broly purple in every way possible as well as greatly weakening transforming units like kaioken goku. However, ssj god goku is usually stronger than beerus as beerus is only limited to the god team which has 2 members currently while ssj god goku also has a saiyan team to back him up and saiyan z-abilities to buff his stats. Therefore, I think ssj god goku is better than beerus of right now.

Summoning more characters depends on your circumstances. If you are a new player who is starting out, you should spend equally on all banners to own more characters and this allows you to create more and better teams due to having more z-abilities to choose from. If you have decided to collect specific characters no matter what the cost, it should be fine to spend more and try your luck. If you choose to be free to play but wish to excel in pvp, you should wait for the next banner if you are only missing ssj god goku.