Depend how much VC funding/ hosting credit obtained [1][2], if bootstrapped and selfunded (money matter) then bare metal [3][4][5].
[1] https://azure.microsoft.com/en-us/pricing/member-offers/bizs...
[2] https://aws.amazon.com/start-ups/
[3] https://www.soyoustart.com/en/
[5] any other provider (softlayer,packet,...)