The Britax Decathalon is by far Britax's best seat.  I researched all the car seats available and decided I would definitely by a Britax, but I wasn't sure which to buy.. After a lot of thought and in-store test browsing, I decided on the Decathlon.  Obviously, any Britax is a great choice, but the Decathlon is heads above the rest.

1.  The crotch slots- No other Britax convertible has more than one crotch slot... the Decathlon has 3!  It is better for little babies and will be more comfortable for older toddlers.

2.  The push button adjustment- Many people complain about this feature because they think it is harder to adjust than the toggle type adjustment Britax uses on most of the other models, however, I like that it is a little harder to adjust because my toddler will not be able to mess with it.  I read several reviews stating that toddlers figured out the toggle type adjuster and were able to loosen their own harness. 

3.  The harness slots are .5 inches higher than the other seats that go to 65 lbs. 

4.  All the pillows are great for babies who are small and tend to get "lost" in larger seats.

Britax car seats (in general) are better than any other brand of car seat for many reasons:

1. SO easy to install.. trust me, I have installed my fair share and no other seats ever fit as well or as easily as the Britax seats do.

2.  They are so sturdy once installed (with or without LATCH) you cannot move them even a millimeter to either side or front to back.

3.  They have built in lock off clips.. this is worth spending AT LEAST $50 more on these seats.  Have you ever used one of the regular car seats (Graco, Evenflo, etc) lock off clips?!?  They are beyond a pain in the neck to install!  Not with Britax, they just clamp down on the reg. seat belt (once you have it as tight as possible).  So easy! 

4.  The LATCH system on the Britax models is heads above the flexible LATCH you see on most car models...  The Britax LATCH is easy on and easy off.. the others are somewhat easy on, almost impossible to get off (unless your seat isn't installed tight enough).

5.  Most Britax models fit children up to 33 lbs. rear facing and 65 lbs. forward facing.. Granted, most people will not need these large weight limits, but just in case.. Or if your child is like mine (75% for height), the height requirements will last throughout toddlerhood. 

6.  Britax models harnesses can all be adjusted easily in forward or rear facing mode... not true of many of the cheaper car seats.

Hope this helps!  Buy a Britax!  You won't be sorry!!!!!