I know most people have recommended against a toddler bed and to go straight for the twin bed, but...
That is the advice I got from EVERYBODY when I was ready to buy a toddler bed, so I didn't get one, and now wish I had. We went for the big boy bunk beds (un-bunked at this point, of course) because we had a another boy on the way at the time, and felt that was the most economical way to go. My son does not like the twin bed, becasue it is just too big and too high for him. He is a restless sleeper and moves a lot, so I feel like a smaller bed, closer to the ground would have been the ideal choice for him. Even with the rails, he fell once because they don't go all the way to the end of the bed, and he ended up scooting down that way in his sleep. We did get him to continue sleeping in the bed after that, but it was a continuous struggle, so has been sleeping on the floor next to his bed for three months. We let it go and will try again in a month or so.
I say do what you think is best for your child. You know his sleep habits and personality the best, so maybe a toddler bed is a better choice for him than a twin bed. Anyway, don't let everyone talk you out of it, like I did. Hope this helped, and good luck with your bed search (sorry I couldn't be more helpful with that).