If you *CAN* meet the 250 hours of "directly involved" in the management of each individual property on it's own, then there's no need to aggretate the properties into a single enterprise. However, if aggregating all three properties into a single enterprise "will" enable you to meet the 250 hours requirement, then you can do that. However, be aware of the following:
When you aggregate your rental properties into a single enterprise to qualify for the QBI deduction, then you can not de aggregate later. Once done, it's done. Therefore, you can not realize any of your carry over losses until the tax year you sell the last property in the aggregate. This can produce quite a tax issue should you convert one of the properties to personal use in later years as your primary residence or 2nd home. You just won't be able to realize all of your carry over losses until all properties are sold or otherwise disposed of. For the purposes of carry over losses, a conversion to personal use is not a disposition. (It can be a disposition for other things, just not for carry over losses)
