I think that any active breed kitty (e.g., Siamese, Highlander, Chausie, Bengal, Abyssinian, etc.) would do well with Teeka. You should be able to gauge how she will bond with a new kitty based on how bonded she was with your Siamese. If she was still closely bonded to you when your Siamese was her companion, I wouldn't expect that to change.
As for whether to get a male or female, if you plan on having them both altered it may not matter, but in general females (even if spayed) tend to be more assertive, bossy, and territorial, so relations are typically smoother if you get a male companion for your female cat, however again, a female may not be any problem either.
As for generation if you do decide to go with another Savannah, I don't think this much matters either as long as you find a kitten whose personality matches Teeka's active, playful lifestyle.