So in First Round, you can use The Usual Suspects: Volt, R-99, Spitfire, Flatline, Wingman In the second round, you can use Budget-Friendly:30-30, G7 Scout, Longbow, Alternator, Havoc. There are also Super Saver guns: EVA-8, RE-45 these are the cheapest and can be upgraded. In the end, it’s not guns it’s you who count.

https://dotesports.com/apex-legends/news/the-best-guns-to-buy-for-your-first-round-in-apex-legends-arenas