Whilst Roland make excellent keyboards their BK models are quite old and they do not seem to be supporting them as Korg and Yamaha support their keyboards in this sector of the market.
The EK50 is Korg’s entry level keyboard in the Arranger market although they call it an Entertainer Keyboard. It is not one that I have played but it does have onboard sounds that I am familiar with have owned a couple of Korgs.
Quite a bit more expensive than the EK50 is their Pa700 which has more than plenty of organ sounds all of which are fully customisable. There is even a virtual Drawbar organ when the Drawbars are operated via the touch screen LCD. The 700 imo is the best in class for overall sound and build quality. Downside is learning the Korg OS takes some effort but once learned it is quick and easy to then call up what you want.
Throwing a curveball then there are Drawbar Organ Apps available for iPad/iPhones in particular Galileo 2 which I have and can recommend it, a drawbar organ App for a few $. Connect up to a cheapish MIDI keyboard and you are good to go for not a lot of cash but there is a rub, in that you need to spend a few hundred to get one with 61 keys and a reasonable feel to the keybed.