I think that it really depends on you and the child...
Do you have the money for a regular bed?
Do you want to get a toddler bed and then have to get a regular bed?
How long will a toddler bed fit the child? Will you use it for another child?
Personally I think that toddler beds are over rated... with my oldest, she went into a queen size bed at 14 months because of our move out of state... it worked out fine.
#2 she was climbing out of her crib before she was a year so we bought a toddler bed (from a friend w/out matterss $20 or so...) she hated it and didn't sleep well on there at all. We had a twin matterss from the top bunk that we weren't using, so we put it on the floor and she did great on there(she is 9 now)...
Along comes #3 and my Mom decides that she is going to get him a toddler size race car bed. I put him in there around 14 months, not because he was done with the crib, but because he is tall and I wanted him to use it before he outgrew it! Needless to say that he was in there till he was about 2 and would hit the sides, have his arms/legs hanging out of bed... so we put him in a twin size, he does great in there (now 4).
With #4 my Mom again, yes, decides she needs to get this hand made bed from a friend of hers.......... the bed is really nice and we paint it to match her room... she starts not liking the crib around a year...waking up smashed on the side, sticking out... wanting to climb out... we put up the toddler bed. She goes to sleep fine in it, but somehow wakes up by smashing her face against the bed and has a black eye... I went that day and bought her a twin mattress and frame and we have had no more problems!
So for me, I think that I would go with a twin, you will get more use out of it... unless your child is on the smaller size and/or likes smaller places to sleep... I have a friend that had her little girl in a toddler bed till she was 5, yes, 5!! I had a hard time beliving that till I saw it!
You have to do what you think is best for your child!
Good luck in deciding!