Normal starts:
1) 20/20 (Treasure)
2) Cricket's Body (Treasure)
3) Cricket's Head (Treasure / Golden Chest)
4) Dead Eye (Treasure)
5) Death's Touch (Treasure / Devil)
6) Dr. Fetus (Treasure)
7) Epic Fetus (Treasure) - considered the 2nd best start
8) Ipecac (Treasure)
9) Lil' Brimstone (Treasure / Devil)
10) Magic Mushroom (Treasure / Boss / mushrooms)
11) Mom's Knife (Treasure / Devil) - considered the best start
12) Monstro's Lung (Treasure)
13) Polyphemus (Treasure)
14) Proptosis (Treasure)
15) Sacrificial Dagger (Treasure / Devil)
16) Tech.5 (Treasure)
17) Tech X (Treasure)

Borderline starts:
18) Chocolate Milk (Treasure) - some people start it
19) Judas' Shadow (Treasure / Devil) - some people start it; it is a low DPS increase on Judas; decent probability to miss B2 DD

Honorable mentions:
- Mutant Spider (Treasure) - nerfed from Rebirth since the shots spread out more; also increments the special counter

Statistics:
- 277 items in the Treasure Room pool
- 17 / 277 = 6.1% chance to find a start per item seen