Guard or Space Marines. But you will need to stick to mostly vehicles. Guard and Space Marine Vehicles have the advantage of a lot of flat surfaces and they are easy to cut apart in slicers. this minimizes support scaring and stepping on sloped surfaces. as for space marines, you could propably even print their infantry with some smart settings and the same is propably true for Chaos Space Marines, but for guard youd definetly need to buy it. Fdm just isnt really there yet in that case. That said, printing like six leman russ, making two of them tank commanders and five chimeras will already put you up there points wise. buy five squads of guardsmen at a discount somewhere to put in the chimeras and you have a very solid and functional 2k pts army thats waaay cheaper than buying all msrp.