We used a potty chair. The Baby Bjorn one. My daughter really liked it and helped pick it out. My son has also taken to it well. We bought 2-3 and put one in each bathroom. That's the neat thing about a potty chair... you can put it anywhere since it's portable, and keep it close by.
Or, you can use a toilet seat ring. It's up to you. If using a toilet seat ring, get a stool step so they can get up on the toilet themselves.
We used both actually. By daughter would use both.
Main thing is that they like it. Each child is different.
But many of the other styles are "cute"...but I found, at least with my daughter, they will only use it if they "like" it. I trained my daughter at 2 years old...so by this time she could "assist" and express which one she "liked" out of the ones which I thought were best.
Being in daycare, many will usually potty train too. So that will be great... and perhaps accelerate the process or at least reinforce the training that are doing. It did for my friend's son and daughter.
It will be an up and down process in terms of perfection. But that's fine. They don't have total bladder control yet...but can and do potty train. Each child will have their own pacing... and levels of cooperation or completion. Main thing is don't pressure them.
Good luck!
~Susan