It depends but over time I think having your own server outweighs renting one but you gotta keep in mind that electricity costs, up time, and all those other things are included in the cost of renting a server. Having you're own hardware will put all that on you. Plus I've heard that servers can get noisy so you'd need to deal with that. However, as a negative for renting, you don't own the hardware you're renting so you'll need to continue paying for it month to month. Depending on the scale you farm at, monthly costs could add up to the cost of buying your own server within a few months.