I would suggest a short scale bass (30") would probably feel most familiar to you as a guitar player but with cheap basses, short or long scale, beware that some of them are not very accurately fretted and go out of tune as you go up the finger board, even some from a manufacturing pedigree you might think you can trust. If you can try before you buy I would recommend you do so and check the intonation, rather that just buy something online and hope it's OK. An out of tune bass on your recordings will sound just awful. I've had students who have fallen into this trap, who would have done better to have got some advice and paid a bit more in the first place rather than end up with some worthless junk and still have to spend the money.