We've done both. The characters are cool and setting are cool at garden grill. It's better to see the plants, etc if you are seated on the lower level. I personally am not wild about the food options at garden grill me they can't really get you anything else if you don't like it. I like the food much better at TE and it's kind of a fun show. It's similar to any hibachi place. Their rice is a little different then fried rice you at most places though. They will give you white rice instead if you like and last time we went they gave me a free rice refill. If you haven't been to a hibachi place before its especially cool. Also note if you have less than 8 ish people others may be seated with you there (can be fun).
I like the food and character interaction at Garden Grill but we will not be going back because the restaurant rotating bothered my wife. Teppan Edo was alright but we have an outstanding upscale hibachi restaurant near us and Teppan Edo didn't hold a candle to it. Last year we tried Tokyo Dining and really enjoyed it. It is in the same building as Teppan Edo and has a pretty large menu if you want to give that a look.