I know it's been said already, but I will say it again. Start with a four banger, and this is why; it will get you out of that guitar mentality. No offense to my brethren that play 6 or more strings, but for a guitar convert like yourself, if you go that route you may just feel that you are playing an oversize guitar. Since you are looking to convert that may not be such a good idea. Playing bass requires a completely different mind set than playing guitar. Start with a four Bro'!