I think Gardiner's SF is extremely good (though I agree with SH about his R&J), haven't heard either Norrington though.
I seem to have a strange assortment of
Symphonies fantastiques: Norrington/London Classical Players, which I quite like, Boulez/LSO (which is what it is, I suppose), and MW Chung/Opera Bastille, which I think is quite good for a more-or-less-what-you-expect approach...
(The Boulez is part of a cheap 3-CD Sony
box that also includes
Lélio, a piece I have a lot of time for due to its fundamental weirdness, as well as
Nuits d'été w/ Minton and Stuart Burrows,
La Mort de Cléopâtre w/ Minton,
Carnaval Romain, and bits and pieces of
Béatrice et Bénédict,
Les Troyens and
Benvenuto Cellini. Not at all recommended for one's only Berlioz, but interesting to have for Hector fanatics like myself...
(looking at the price I just linked to, I guess I can only say that it
used to be cheap
)