Both is top altcoin on coinmarketcap but i Don't investment on DOT personally became this token price is already high and MATIC price still low according to matic chain. because polygon is a very useful chain and it god popularity for low transcation fees. And polygon chain is becoming more popular day by day so its price may increase a lot in future. So I prefer matic between DOT and MATIC.  This is just my personal preference and I would not encourage you to do so. You make your own decision. Don't rush into investing based on someone's advice